About
Built for users who expect better.
Kuroki Studio builds paid Android apps. Every product in the portfolio reflects five non-negotiable principles: not marketing claims, but constraints on every feature, every dependency, every architectural decision.
Five principles
One-time purchase.
Users own what they buy. No subscription tiers, no feature gating behind monthly fees. Pay once and the app is yours, including all future updates within the major version.
No advertisements.
No banner ads, no interstitials, not on the first launch and not after. Advertising requires tracking. Tracking requires data collection. Neither belongs in a utility app.
No accounts required.
Apps work fully offline by default. There is no server to sign up for, no email address to hand over, no password to forget. The app installs and runs.
Local data only.
Your data stays on your device. No cloud sync, no analytics, no telemetry. If a feature would require sending data off-device to work properly, that feature is not built, or the requirement is engineered around.
Polished, modern UI.
Material Design 3 for Android. Clean, purposeful layouts without decorative clutter. The interface is the least interesting part of the product. It should get out of the way.
Context
The gap Kuroki occupies.
The Android paid-app market sits between technically excellent FOSS apps most users have never heard of, free ad-supported apps that treat attention as the product, and subscription apps that charge monthly for tools people use daily.
Kuroki occupies the gap: Play Store presence, one-time purchase, no ads, no account, polished UI. The same audience that pays for indie iOS apps. Underserved on Android.
The name
Kuroki (黒木)
"Black tree" in Japanese. The logo carries that metaphor: deep roots (foundational, durable), bare branches (no excess, structural honesty), surviving form (built to last, not to chase trends). Two syllables. Pronounceable everywhere.