Full-Stack / AI Engineer Intern

◈About the Role

株式会社Social AI is an AI-native startup in Shibuya building PLAYTEST (プレイ検), an edutainment platform that helps kids study and succeed at standardized tests through games with microlearning woven into every moment of play. This is a full-stack role in a small AI-native team: you’ll build LLM harnesses and content-production pipelines, that connect the game engine from the backend through the AI layer to the frontend games served to players. You’ll learn through lean startup cycles, agentic coding in a multi-developer production codebase, with hands-on mentorship and regular in-person meets in Tokyo.

✓What You Will Do

• —Build and ship backend code supporting our edutainment platform and minigames
• —Develop LLM harnesses for education, including prompt pipelines, structured outputs, and evals
• —Build tooling that turns learner mistakes into new questions, materials, and games
• —Connect games to our question bank and AI reteaching backend
• —Work across game backend services and the model layer
• —Prototype new mechanics quickly and playtest them with real users
• —Profile and optimize performance for low-spec school hardware
• —Participate in sprint planning, code review, and product and technical discussions

◎Requirements

• —Student or recent graduate; international students welcome
• —Experience with at least one programming language
• —Strong ownership and follow-through: you take responsibility for work through shipment
• —Comfortable in a fast-paced, multicultural environment
• —Business-level English
• —Available 10–20 hours per week
• —Able to join regular in-person meetings in Tokyo
• —Japanese is helpful but not required

★Nice to Have

• —Python and Typescript / Javascript experience;
• —Experience with LLM APIs, prompt engineering, or model evaluation
• —Backend or cloud experience with APIs, databases, or serverless systems
• —Familiarity with Cursor, Claude Code, Codex, or other agentic development environments
• —Genuine interest in language learning, education, or how games teach
• —One real project we can review or play, such as a game or app