Low-friction,
AI-assisted engineering.

Seiraiyu designs, builds, and operates its own products — each one a focused tool for engineers who move fast with AI.

04 products shipping 流星 ryūsei · shooting star est. 2026
Our brands

Independent tools, one source of gravity.

Each brand stands on its own — its own name, kanji, and voice. Seiraiyu is the constant behind them.

Great developer tools are opinionated, focused, and unmistakably their own. A house brand shouldn't dilute that — it should fund it.

Seiraiyu — 流星, a shooting star — is the still point our tools move around. We handle the parts that don't make a product better when duplicated: billing, infrastructure, hiring, the long-term roadmap.

Everything customer-facing belongs to the brand. kisenon doesn't feel like “a Seiraiyu product.” It feels like kisenon. That's the point.

01

Tools, not a portfolio

We build and operate, we don't just hold. Every brand ships real software developers choose to use.

02

Invisible by design

The parent never out-shouts its children. You meet the brand first, the house only if you look.

03

Patient capital

Shared infrastructure and one balance sheet let each tool grow on its own timeline.

Contact

Get in touch

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