Japachar is the tool you need to help you to memorize the japanese characters, it features learning options for Hiragana, Katakana and Kanji, all of this while being completely Free Software so you can inspect all the code.
For privacy concisious users this app never connects to internet or ask any intrusive permissions.
You can get the app for free on paid platforms in exchange for testing AlgaOS apps for the goal of 12 testers, consult opportunities here: Join as tester.
Study words from multiple word lists or the complete dictionary