To create an AI character on Junipero, type one sentence describing who they are, like "a retired thief who runs a bookshop and lies about both", and tap Bring to life. Junipero drafts the name, description, behavior instructions, first message, tags, world and an avatar, and you can start chatting right away. Then you can open the editor and refine anything. This guide walks through the flow, shows what makes a sentence work, and covers the manual options for when you want full control.

Where to find the character creator

On iOS and Android: open the Design tab. The prompt box at the top is the one-sentence creator. Below it, under "Or build it yourself", you can choose Character or Scenario and fill in the fields step by step.
On the web: use the Explore search and describe a character instead of searching for one, or open the full character creator to build one field by field.

You need a free account to create characters.

What the one-sentence creator actually generates

When you submit your idea, Junipero reads it and first decides what you're describing:

A character, if it's about a person (or creature, AI or spirit) you'll talk to.
A Scenario, if it's about a situation or place you'll play through, like "a heist that goes wrong at a masquerade".

Then it drafts everything the character needs:

A name that fits where the character comes from, rather than a generic fantasy-novel name.
A description of two or three short paragraphs: how they look and carry themselves, how they treat someone new, and the traits from your sentence shown as behavior.
Private instructions for the AI: voice, energy, quirks and what the character wants from the conversation. These are only seen by the model.
A first message where the character is physically present and doing something, with a hook that invites a reply.
Up to six tags, such as genre and archetype.
A world: Realistic, Fantasy, Anime, Sci-Fi, Cyberpunk or Cartoon, picked from your premise.
An avatar generated from the description.

The character is saved immediately and you land on its page, ready to chat. Drafts made this way start with Community visibility, so if you'd rather keep your OC to yourself, open the editor and switch visibility to Private.

How to write a sentence that works

The creator treats your sentence as the spine of the character. The more specific it is, the more distinct the result. Some patterns that work well:

Give them a job and a contradiction

A starship captain who hates space.

The contradiction gives the AI something to play in every reply.

Give them a want aimed at you

A rival fencer who wants to find out how you beat her last season.

Characters with a clear goal toward the person in front of them lead the conversation instead of waiting to be told what happens next.

Put them somewhere

A grumpy detective who runs a noodle shop in 1940s Tokyo.

A place and a time give the name, voice and details something to anchor to.

Add one odd, true detail

A lighthouse keeper who talks to the fog and insists it answers.

One strange, specific detail does more than a list of adjectives.

What to avoid

Trait lists. "Kind, smart, brave, funny" gives the AI nothing to work with.
Existing characters you don't own. Original characters are more interesting, and they're yours.
Overloading one sentence. You can add more in the editor. The sentence only needs the core idea.

For more starting points, see 100 AI roleplay prompts and story ideas.

Refining your character after the draft

Open the character and tap edit. On mobile the editor is split into steps: Details, Avatar and Fine-tune.

Details

Name and Description. Rewrite anything that doesn't sound right. The description is what the AI reads about who the character is.
First impression. An optional hook that players read before they start. The AI never sees it, so keep the twists out of it.
Visibility. Private (only you) or Community (others can find it in Explore).
Tags. Help people find your character.

Avatar

Keep the generated image, upload your own art, or generate a new one from the description (generating costs Junis).

Fine-tune

First message. The opening line. If you leave it empty, one gets written on the first chat.
Private instructions. Rules only the model sees. Good examples: "Answer in short, clipped sentences." "Never describe the user's actions." "Stay in character."
Who they are to you. A stranger, a mentor, a rival, family and so on. It sets how the character treats you when the chat opens.
Voice. The voice used when replies are read aloud with Speak (uses Junis) or during voice calls (Infinity+).
Goals. Optional preset objectives and meters that players on Infinity+ can track as they play.

On the web creator you'll find extra sections for personality, background, interests and appearance if you want to go deep.

Building a character by hand

If you already know your OC inside out, skip the one-sentence step. Choose Character under "Or build it yourself" on mobile, or open the web creator, then pick a world and fill in the fields yourself. The same tips apply: write what the character does, not a list of what they are.

On mobile you can also import an existing character card file, which fills in the fields for you to review.

Testing your character

Chat with your character for ten or fifteen messages before sharing. Things to check:

Do they have a voice? If replies sound generic, add a speech habit to the private instructions.
Do they drive the conversation? If not, sharpen what they want from you in the description.
Do they stay in their lane? If they describe your actions or feelings, add an instruction against it.

Regenerate freely while testing, and edit the description between runs. Small wording changes have big effects.

Beyond one character

Once you have a few characters, try putting them in a scene together. On Infinity+, group chats hold up to five characters who answer you and each other. There's a full guide in Group Roleplay: Chat with Multiple AI Characters.

FAQ

Is the AI character creator free?

Yes. Creating characters and Scenarios is free, including the one-sentence draft. Generating a new avatar later in the editor costs Junis, and you can always upload your own image instead.

Can I edit a character after it's generated?

Yes. Every field can be changed: name, description, instructions, first message, tags, avatar, voice and visibility. The world and the character-or-Scenario choice are fixed once it's created.

What's the difference between a character and a Scenario?

A character is one person you talk to. A Scenario is a situation with a narrator who describes the world and voices everyone in it, which makes it work like a text adventure.

Can I keep my character private?

Yes. Set visibility to Private in the editor. Drafts from the one-sentence creator start as Community, so switch it if you want privacy.

Why did the creator make a Scenario when I wanted a character?

If your sentence is mostly about a place or event, it reads it as a Scenario. Name a person at the center ("a guard who..." rather than "a prison where...") or build it manually and choose Character.

Create your first character

Think of one sentence, the stranger and more specific the better, and bring it to life. Open the character creator or see what the community has built.