How do I add Koseisa to my phone?

Koseisa installs straight from your browser, so you don't need an app store.

On Android: open koseisa.com in Chrome, open the site menu and tap Install the app.

On iPhone: open koseisa.com in Safari, tap the Share button, scroll down and tap Add to Home Screen, then Add.

After that, Koseisa opens from its own icon like any other app.