Any backend, embodied
Chat Completions, the Responses API, or a push WebSocket. Emotion, motion, voice tag and caption arrive as generate_express cues beside the reply, so she reacts instead of just answering.
The head.
Not the brain.
A VRM character who lives on your desktop, watches the cursor, and speaks when the agent you connect has something to say.
She lives on your windows
She perches on a window top, peeks around a side edge, strolls the floor, and jumps between windows. Dropped in mid-air, she falls to the first surface below and lands.
She speaks first
Screen changes, quiet stretches and set times fire cues to the backend. Whether to say anything is the backend's call; YUI only renders what comes back.
YUI is the body. Your agent is the brain.
YUI ships no model. It renders, senses and fires; judgment, persona and memory belong to whatever you plug in, so she is exactly as smart and as yours as that backend.
YUI does
- VRM rendering, lipsync, expressions and motions
- Text and voice input, screen capture
- Speech bubble, status pill, settings
- Firing proactive cues on a schedule or a screen change
Your agent does
- The agent loop, memory and tools
- Persona and mood
- Emotion and motion cues
- Deciding whether to speak at all
What you need
One required piece, and it ships in the repo. Add a brain and a voice when you are ready.
Required A VRM model. A default one is bundled; bring any VRM 0.x or 1.0 file to replace it.
Chat backendAny OpenAI-compatible endpoint, a Responses API agent, or a push WebSocket.
Expression brokerDeprecated, removed in v0.6.0: the client declares its tools on the request.
TTS providerIrodori TTS Server or any OpenAI-compatible speech endpoint.
STT and VADSilero VAD segments speech; any transcription server turns it into text.
Reference voiceA clip to clone the character's voice, uploaded from the panel.
Standalone ModsIndependent MCP servers: router, desktop control, shell sandbox, avatar.
Custom expression setMap emotion cues to your VRM's own blend shapes.
Ready to wire her up?
Get started