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Case study

Protagonist: an AI social world where you are the lead

An AI-first social app from a US-Japan team where users star in their own world of conversations, virtual friends, and storylines. We built the real-time chat backbone, character generation pipeline, and monetisation layer.

Protagonist (HQ Amerika Serikat & Jepang) · 2025

AISocialMobileEntertainmentGenerative AI
Protagonist AI social world home screen
Conversation with AI characters
Personal storyline flow
AI-powered social feed
User protagonist profile

Project context

Protagonist is an AI social app where users are the lead in evolving conversations, virtual friends, and storylines. The product team spans the US and Japan with a global audience.

Challenge

AI generation scale and real-time multi-character chat must stay consistent: faces, voices, and personalities must not drift mid-story. Monetisation must feel natural without breaking immersion.

What we built

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Low-latency multi-character chat engine with per-session state management.
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Long-term memory per user so characters remember decisions and preferences.
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Image, voice, and persona generation pipeline with auditable templates.
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Subscription and in-app purchase monetisation integrated with app stores.

Results

A global community with strong retention; users return daily to continue their story. Founders focus on content and community while Lunexia maintains the chat and AI foundation.

Protagonist: an AI social world where you are the lead | LUNEXIA