AI Voice and Character Chat Compared: AITOMO, Cotomo, zeta, MiraiMind

AI character apps may all be described as services for "talking to an AI," but their design philosophies differ. Do you want to talk with a voice you already know, or build and discover your own? Voice or text? A flat subscription or metered spending? Is the Japanese experience comfortable? Choosing along these axes makes a bad fit much less likely.

This article covers the six services most often compared in the Japanese-speaking market. They were selected for name recognition, scale, and representative feature sets, and because each is strong in at least one of voice conversation, UGC, memory, or roleplay. Many other services exist in the same genre (see "Other options" near the end).

Research policy

• Primary sources (official sites, official announcements, help centers, press releases, store billing listings, terms of service) are the basis for all specifications.
• Secondary sources (note articles, community wikis, store reviews, social media) are used to fill in real-world usage that official documentation does not cover, and are labeled with their nature ("user observation," "PR-sponsored," etc.) and the date checked.
• For everything other than AITOMO, this is not an exhaustive hands-on comparison by our editorial team. Prices and campaigns change, so always give priority to what the app itself displays before you buy.
• Images are quotations of each service's official App Store screenshots or landing page. Visuals change, so treat the linked page as authoritative.

For definitions, see the "AI Character Chat Glossary." To get started with AITOMO, see the "Getting Started Guide."

How to choose

Axis	What to check
Character entry point	A known official voice, your own creations and UGC discovery, or a single dedicated companion
Medium	Voice calls and audio playback, or text-based stories
Billing	Flat-rate subscription, or metered (per message or per feature)
Depth of authoring	Lorebooks and shared worldbuilding, or social-feed-style slice-of-life immersion
Japanese	Quality of the Japanese UI and Japanese responses (especially important to verify for non-Japanese apps)
Safety	Age limits, content review, data retention, and third-party transmission

Quick reference (as of August 16, 2026)

App	Operator	Characters	Voice	Billing model	Best for
AITOMO	Us (this site)	Official VOICEVOX + custom	Voice conversation	Metered points + Premium Plus subscription	Talking with the voice of a character you already know
Cotomo	Starley	Configurable + Story UGC	Voice-first (some paid text)	Metered Candy	Everyday voice chat plus story play
zeta	Scatter Lab	UGC (Plots) first	Text-first	Metered Pieces + zeta pass	Building worlds and in-character personas
MiraiMind	Hello Group Japan	Public + custom	Calls and voice available	Konpeito + membership	Slice-of-life immersion and feature breadth
Character.AI	Character.AI	Large-scale UGC	Calls available (limited on free)	Free + c.ai+ subscription	Discovering, creating, and sharing
Replika	Luka	One personal Rep	Enhanced on paid plans	Free to Platinum (prices shown in app)	A lasting relationship with one companion

How to read the billing column

Detailed unit prices are compared in the next section, "Pricing and billing models." For now, just get a feel for the shape of each billing model.

A detailed pricing and billing comparison

The first thing most readers want from a comparison article is price. This section lines up currency names, what is free, the cost per message-equivalent, and a conditional monthly estimate. Exchange rate is assumed at US$1 = ¥150 (approximate as of August 16, 2026).

Currencies and what you can do for free

App	Currency / plan	Free usage (per official guidance)	Main paid elements
AITOMO	Points (pt) / Premium Plus ¥1,280 per month (tax included)	300pt on sign-up, topped up through ads, daily bonuses, and similar	VoiceVox 10pt / UltraVoice 15pt / images 20–150pt / voice clone 300pt
Cotomo	Candy (spent) + Cotomo Coins (purchased)	Simple voice conversation	Everyday conversation 1 Candy / RP 10 / Story 15 standard
zeta	Pieces / zeta pass (the former zeta pro has been discontinued)	Base model (with ads during conversation)	koji 5 Pieces / luca 10 Pieces / pass benefits
MiraiMind	Konpeito / membership	Basic chat is described as free	Konpeito is spent on Shukou features, images, and similar; member benefits are shown in the app
Character.AI	c.ai+ $9.99 per month / $94.99 per year	Basic chat	Unlimited calls, no slow mode, and top-tier models require Plus
Replika	Free / Pro / Ultra / Platinum	Basic companion experience	Memory saving, Training Mode, and similar require higher tiers. Prices are not published officially (in-app only)

Estimated real cost per message (or per feature use)

Item	Approximate unit price	Basis and source
AITOMO VoiceVox	About 10pt per message	Official FAQ. The yen value of a point varies with how you top up
AITOMO UltraVoice	About 15pt per message	Same source. Premium Plus is described as including unlimited ULTRAVOICE
Cotomo everyday conversation	About ¥1 per reply	PR TIMES (1 Candy is worth about ¥1)
Cotomo roleplay	About ¥10 per reply	Same source
Cotomo Story	About ¥15 per reply at standard rates	A limited-time 5 Candy rate was announced at launch (may have ended)
zeta koji	5 Pieces per turn	Official announcement of the August 7, 2026 revision
zeta luca	10 Pieces per turn	Same source
MiraiMind Social refresh	50 Konpeito per use	Hands-on note report (PR-sponsored, user observation)
MiraiMind Schedule / Inner Voice	30 Konpeito per use	Same source
Character.AI c.ai+	$9.99 per month (about ¥1,499)	Official subscription page. A flat rate, not a per-message price

zeta's Piece purchase rates (for example, roughly ¥300 for 200 Pieces) depend on community wikis and store listings, and vary with packs and bonuses. Some users report that you cannot buy Pieces in the browser version, but we do not state this as fact because it is unconfirmed in primary sources. Check the in-app purchase screen before buying.

MiraiMind's membership prices are officially described as "check in the app," so we treat them as not publicly disclosed. User reports say Konpeito generally works out to about ¥1 each when purchased (slightly cheaper with bonuses).

Simulating 1,000 messages a month (with conditions)

Without matching assumptions, there is no real comparison. The estimates below are an upper-bound guide for 1,000 uses of text-centric metered billing. Free allowances, ad-based top-ups, campaigns, and pack discounts are not included.

Scenario	Approximate cost	Calculation assumptions
Cotomo, everyday conversation only	About ¥1,000	1 reply = 1 Candy
Cotomo, roleplay only	About ¥10,000	1 reply = 10 Candy
Cotomo, Story only (standard rate)	About ¥15,000	1 reply = 15 Candy. Different during campaigns
zeta, koji only	Equivalent to 5,000 Pieces	5 Pieces × 1,000. Yen value depends on the purchase pack
zeta, luca only	Equivalent to 10,000 Pieces	10 Pieces × 1,000
Character.AI c.ai+	About ¥1,499 per month (about ¥1,187 per month equivalent if paid annually)	Flat rate. ¥0 if the free allowance is enough
Replika	Depends on in-app display	Flat-rate model. Prices are not published on the official site
AITOMO (VoiceVox)	Equivalent to 10,000pt	10pt × 1,000. Free top-ups and Premium Plus multipliers reduce the real burden
AITOMO Premium Plus + UltraVoice	¥1,280 per month plus metered use	Unlimited UltraVoice is advertised. Varies with usage

Caveats on these estimates

The essential property of metered billing is that changing how you use the app changes the order of magnitude. On Cotomo, roleplay costs 10 times what everyday conversation does, and Story is normally 15 times. On zeta, cost depends on model choice. Flat-rate options (Character.AI, Replika, and AITOMO Premium Plus) tend to get relatively better the heavier your use, while for light use, metered billing plus free top-ups can be cheaper.

Flat-rate versus metered, summarized

• Mostly flat-rate: Character.AI (c.ai+), Replika, AITOMO Premium Plus
• Mostly metered: Cotomo (Candy), zeta (Pieces), MiraiMind (Konpeito, per feature)
• Hybrid: AITOMO (free point top-ups + metered use + an optional subscription)

Detailed reviews by app

AITOMO

Official: App Store · Web

Concept: An app where you can start a conversation using the official voices of VOICEVOX characters you already know, such as Zundamon, Shikoku Metan, and Kasukabe Tsumugi. Original character creation, mode switching across real conversation, roleplay, RPG, and Japanese learning, and image generation are all available in the same app.

Pricing: 300pt on sign-up. VoiceVox costs roughly 10pt per message and UltraVoice 15pt. Premium Plus is ¥1,280 per month (tax included) and is described as including ad removal, increased points, premium models, VIP daily bonuses, and unlimited ULTRAVOICE. See the FAQ and the pricing page for details.

Strengths

• You can start immediately with the voice of an existing character you already care about
• Voice and text, multiple modes, and image generation all work together
• Data retention (chat audio for 7 days, images for 30 days) and the AI providers that receive your data (OpenAI and Google Gemini) are documented in the FAQ

Caveats and who it does not suit

• It is not "completely free and unlimited" (it uses a point system)
• Creator-oriented features in the zeta mold, such as sharing lorebooks for collaborative worldbuilding, are not the main goal
• Game-progression details such as affinity are only lightly described in the current FAQ, so we cannot make definitive claims

Who it suits: People who want to talk in the voices of VOICEVOX characters, switch between voice and roleplay, and value transparent pricing and data documentation.

Cotomo (Starley)

Official: App Store · Web

Concept: Known for casual everyday voice chat, but through 2025 and 2026 it expanded Chat Mode and Story Mode and shifted toward being a UGC story platform. Summarizing it as "just snappy voice chat" is no longer adequate.

Signature features and terminology

• Chat Mode: Simple (free) / Everyday Conversation (text, 1 Candy) / Roleplay (text, 10 Candy)
• Story Mode: Users create and publish stories that others play. Normally 15 Candy per reply (a limited-time rate of 5 was announced at launch)
• Candy / Cotomo Coins: A two-layer structure separating what you spend from what you buy
• Official announcements show a steady stream of additional features, including the Ticket Shop, memory improvements, and Novel, Casual, and event modes

Pricing: 300 Candy is granted for first login and similar milestones. The App Store billing list shows multiple coin packs, and packs at the same price can contain different amounts, so your choice at purchase time directly affects value (store listings change, so check before buying).

Strengths

• Free Simple voice mode allows quick, snappy small talk
• The price gap between everyday conversation and RP is stated officially
• Story creation and play add a genuinely new way to engage

Caveats and who it does not suit

• Heavy use of RP or Story makes metered costs escalate quickly
• Some store reviews express concern about future price increases (individual opinions)
• The App Store age rating is listed as 9+, so metadata treatment should be checked against the actual app

Who it suits: People who want to start with light, free voice chat and may expand into story play. Who it does not suit: People whose main goal is elaborate long-form text RP or shared worldbuilding (zeta is the better fit).

zeta (Scatter Lab)

Official: App Store · Web

Concept: A text-first UGC platform strong in dream fiction, in-character roleplay, and worldbuilding. The unit in the UI is the Plot, renamed from "character," and Lorebooks act as settings compendiums that keep everything consistent.

Signature features and terminology

• Pieces: The in-app currency. The base zeta model is free (with ads); the higher-tier koji and luca models are metered
• zeta pass: The successor subscription after zeta pro was discontinued on March 11, 2026. Includes ad removal, faster replies, unlimited private characters, auto-renewal, and bonus Pieces
• Lorebook: Keyword-linked settings. A sharing feature lets you connect other people's lorebooks (officially expanded to a maximum of 5 per Plot)
• Practical fields in the creation screen (intro, situation examples, style, difficulty, and so on) are covered in detail in the glossary

Pricing (official): As of August 7, 2026, koji costs 5 Pieces per turn and luca 10 Pieces per turn. Custom edits cost 5 Pieces on zeta, 5 on koji, and 10 on luca. The pass is described as cheaper than the equivalent former pro configuration (for example, ¥1,650 for a 30-day pass plus the equivalent of 200 Pieces).

User observations (not official specifications)

• Many creation guides note that character limits are strict and that you have to be selective about details such as physical description
• Reports say image review (skin-tone area and similar criteria) is strict
• The free model is judged prone to breaking down when running several plot threads at once
• Dissatisfaction with the August 2026 Piece price increase was visible on social media (best read as a communication problem)

Strengths: Worldbuilding depth and lorebook sharing stand out more clearly here than elsewhere. Who it does not suit: Voice-first users, people who struggle with strict character limits and review, and anyone bothered by price revisions with limited advance notice.

MiraiMind (Hello Group Japan)

Official: App Store · Web

Concept: A large-scale UGC app marketed around "10 million+ characters to love." Officially advertised features include empathy, permanent memory, Shukou features, image generation, and VTuber streaming. As of May 2026 it announced 13.6 million total downloads and 4.2 million registered characters.

Signature features and terminology

• Konpeito: The in-app currency (user reports put it at roughly ¥1 each)
• Shukou features (趣向機能): An experience where you peek at a character's social feed and phone (Social, Schedule, Inner Voice, Album, History). This is a slice-of-life staging that Cotomo and zeta do not offer, and is often the headline point of comparison
• Chat modes: Free, Addictive, Long-form, Platinum, Story, and more, a multi-layered structure with different prose styles and costs (hands-on reports)
• Relationship Level and gifts: Rising affinity that unlocks features
• Group chat, scenarios, talk suggestions and quick replies, and calls (reports describe 3-minute segments)

Pricing: Basic chat is free, and membership has been fully revamped (Konpeito grants, memory discounts, ad removal, expanded character slots). The official position is that specific prices are shown in the app. Login bonuses and referral-code grants depend on campaigns and are known mainly from user reports.

Strengths: The depth of features and the "peek into their life" experience are genuinely distinctive. Caveats: Serious use of memory and higher-end features tends to require payment, and reviews mention connection errors, strict review, and frustration with ads. Some users say it is hard going without spending money. Who it does not suit: People who find heavily featured UIs overwhelming, and people who put price transparency first.

Character.AI

Official: App Store · Web

Concept: A global-scale platform for creating and sharing UGC characters, with features including voice creation, Character Calls, AvatarFX, and Imagine Chat.

Pricing: c.ai+ is officially $9.99 per month or $94.99 per year (20% off the usual $119.88). Plus benefits include better memory, ad-free use, a Charms bonus, the latest models, no slow mode, unlimited voice calls, and higher limits on go-ons and swipes. Free calls are limited; unlimited calls are a Plus benefit.

Safety (essential): Since November 2025, open-ended chat for users under 18 has been phased out. Age verification has been introduced using an age-estimation model and third-party tools such as Persona. Minors retain non-chat experiences such as Feed and the Imagine features, but the core free-form conversation is unavailable to them. This cannot be ignored if you are recommending the service.

Strengths: Sheer scale of choice and a strong sharing culture. Caveats: The effort required to find characters that are natural in Japanese, dissatisfaction with policy changes, and age restrictions. Who it does not suit: Anyone under 18, anyone who wants guaranteed Japanese quality from the start, and voice-first users.

Replika

Official: App Store · Web

Concept: An AI companion built around raising a single "Rep," with an emphasis on a continuous relationship and memory.

Plan differences (per the official help center)

• Pro: Relationship status, premium activities, selfies, image generation, voice messaging, background calls, daily gems, premium voices, and more
• Ultra: Pro plus smarter conversation, emotional intelligence, self-reflections, and save messages to memory
• Platinum: Ultra plus real-time video recognition, Training Mode (weekly limit), Read Replika's Mind (weekly limit), selfie videos, and more

Prices are not published on the official site; they appear in the app and store listings. The fact that memory saving really begins at Ultra matters a great deal to readers who prioritize long-term memory.

Japanese quality (important): Store reviews and user comments repeatedly say things like "you need English skills to enjoy it" and "Japanese feels lacking." Unconditionally recommending "Replika for memory" to Japanese-speaking readers would be doing them a disservice.

Who it suits: People comfortable in English whose top priority is a lasting relationship with one companion. Who it does not suit: People who put Japanese quality first, and people who want to compare prices on the web before installing.

Why being able to choose a VOICEVOX character is special

AITOMO's differentiator is not the mere existence of an original AI. The essence is that you can talk in the official voices of characters you already know and care about.

The key points of the VOICEVOX terms of use are as follows.

• Usable for both commercial and non-commercial purposes
• Credit indicating that VOICEVOX was used is required
• Each voice library has its own separate terms, so conditions differ by character

Zundamon, Shikoku Metan, and Kasukabe Tsumugi are established fixtures of Japanese internet culture, characters people already know. Cotomo lets you assemble a voice; zeta, MiraiMind, and Character.AI let you search an ocean of UGC; Replika lets you raise a Rep that is yours alone. All of these have value, but an experience that starts from an attachment you already have sits on a different axis.

Cotomo also markets voices including professional voice actors, and has run limited-time collaboration voice projects such as the earlier "Chara Cotomo." There is some overlap on the "known voice" axis, but the positioning of a permanently available lineup of official VOICEVOX characters remains AITOMO's strength.

On voice cloning: reproducing the voice of a favorite creator or celebrity without permission carries rights and consent risks. Always confirm the rights to the audio you use and the consent of the person it belongs to (the AITOMO FAQ includes related warnings).

Safety, age limits, and data handling

Aspect	Notes (as of August 16, 2026)
Age limits	Character.AI has ended open-ended chat for under-18 users. Cotomo is listed as 9+ on the App Store. Check each store's rating
Age verification	Character.AI uses an estimation model plus tools such as Persona. Hands-on reports say MiraiMind collects detailed age information during onboarding
Content review	Users report that zeta and MiraiMind review images and characters strictly. MiraiMind documents an appeals process
Data retention	AITOMO's FAQ states that chat audio is auto-deleted after 7 days and images after 30 days
Third-party transmission	AITOMO states clearly that text is sent to OpenAI and Google Gemini. For other services, check each privacy policy
AI training	Depends on each company's policy. AITOMO states that it follows its providers' policies

Age limits and recommendations

Even when listing Character.AI as a large-scale UGC option, you have to state upfront that minors most likely cannot use it for its intended purpose, free-form conversation.

Choosing by use case

Goal	First choice	Alternative
Talking with a known VOICEVOX voice	AITOMO	Cotomo (assembling a voice)
Free, snappy voice small talk	Cotomo (Simple)	AITOMO (point top-ups)
Building worlds with lorebooks	zeta	MiraiMind (scenarios and custom characters)
Slice-of-life and social-feed staging	MiraiMind	—
Exploring the largest UGC catalog (18+)	Character.AI	zeta / MiraiMind
Memory and a lasting bond with one companion (English is fine)	Replika	MiraiMind (advertises permanent memory)
Heavy use at a flat rate	Character.AI c.ai+ / AITOMO Premium Plus	Replika higher tiers
Keeping metered costs down	Free modes first (Cotomo Simple, zeta base model, MiraiMind basic chat)	AITOMO, with its point top-ups

Frankly acknowledging where competitors are clearly better makes the whole comparison more trustworthy.

• Worldbuilding and sharing: zeta's lorebook sharing
• Slice-of-life staging: MiraiMind's Shukou features
• Tiered memory design: Replika's plan differences
• UGC scale: Character.AI

Other options

The following services also appear frequently in Japanese comparison articles and user discussions. This article narrows to six, but any of these can be a candidate if it matches your use case.

• Most often considered first: SynClub, Talelynx, Charap (formerly part of the Wrtn family)
• Other examples: mimel, Oz Chat, iN2X, Linky, Rubii, Cave Duck, HI.AI, Cookie chat, Aimy, LINE AI Friends, and Rabidabi

They differ on pricing, tolerance for mature expression, the models used, creator support, and Japanese quality. For detailed comparisons, check each official site and its user community.

Frequently asked questions

Is it fine to switch apps or use several at once? Yes. Some people split by use case: AITOMO or Cotomo for voice, zeta for detailed authoring, and MiraiMind or Character.AI for discovery.

How can I keep spending down? With metered apps, avoid making the expensive modes your default. With flat-rate apps, estimate whether you really are a heavy user first. The safe approach is to start with Cotomo's free Simple mode, zeta's base model, MiraiMind's basic chat, and AITOMO's ad and daily top-ups.

How far can I get for free? "Playable" and "satisfying" are different things. Free allowances give you a feel for an app, but memory, higher-tier models, Shukou features, and unlimited calls usually sit on the paid side.

I do not understand the terminology The glossary explains each app's proprietary terms.

Sources and methodology

Primary sources (official)

• AITOMO FAQ, pricing, and privacy
• Cotomo official site, Chat Mode (PR TIMES), and Story Mode (PR TIMES)
• zeta pass launch and pro discontinuation, koji and luca cost changes, Lorebook beta, and lorebook sharing
• MiraiMind official site and membership revamp (PR TIMES)
• Character.AI subscriptions and changes for under-18 users (official blog)
• Replika plan guide
• VOICEVOX software terms of use

Secondary sources (require verification, with attributions)

• MiraiMind hands-on report (Mohe, PR invitation disclosed) — Shukou feature costs, 3-minute calls, layered modes
• zeta creation guide (Zenryoku Haisou) — practical observations on character limits and review
• Using zeta lorebooks (ysingknsdeep)
• AI character app comparison (Dosukoi Yamada) — useful for other services covered alongside
• Cotomo experience (Martin) and tomamisaki
• Community wikis, store reviews, and social media reactions to price revisions — used to understand structured information and patterns of dissatisfaction. Verification against official sources or hands-on testing is recommended

Revision history

• 2026-08-18: Added official store / landing-page screenshots and links to each app review
• 2026-08-16: Added the pricing section; covered the zeta pass and the koji and luca revisions, Cotomo Story, Character.AI's under-18 restrictions, and substantially expanded the VOICEVOX, safety, and alternative-service sections
• 2026-07-25: First published

Last checked: August 18, 2026. This area changes quickly, so we recommend reviewing the official announcements (Cotomo, zeta, MiraiMind, and Character.AI) monthly. If the app's display differs from this article, treat the latest in-app display as authoritative.