Originally a mirror of the original Kumagusu project but now a fork with enhancements and bug fixes.
https://github.com/clach04/kumagusu_mirror/ is a file based note application for Android. Plain text and encrypted files are stored/organized using directories. The encryption format is compatible with Tombo (dated encryption format).
Related tools like https://github.com/clach04/puren_tonbo/ allow desktop and command line interaction with encrypted files. Including git integration for different and three-way-merge support, plugins for text editors like vim and scite, grep-like tools for searching encrypted files.
For more information about Tombo and chi encrypted notes see https://github.com/clach04/puren_tonbo/wiki/Tombo
APKs are available from https://github.com/clach04/kumagusu_mirror/releases No plans for Google Play Store. Help wanted for F-Droid and/or GitHub Action builds.