Would be great if you add a quick travel option - enter a level you want to go and go there. Because I farm at low levels, it's a bit of a pain to click the left arrow over and over again :)
Idea: include a guide on how to learn Kana more effectively with this game, like pronouncing the Kana out loud every time you see it and so on. Also, maybe you could later implament a Kana drawing game? Just like these few modes that are now available, but there you must draw the image of the Kana with your mouse. Would be fun for touchscreen users :)
Kana drawing sounds fun, but there are too many different typefaces and that makes it difficult to recognize a kana (if you draw a き, how does the game determine whether it is correct?). Besides, it's a better idea to write kana on paper anyway.
Takkun. You. You... I love you! I was learning Kanji and ran out of motivation, despite I haven't learnt Katakana.
This is like a fresh spring of motivation to continue learning Japanese and making the whole process more fun! You're a God, Takkun!
 "Shop Heroes"){kind=icon}
 "Crusaders of the Lost Idols"){kind=icon}
 "50 years (graphical)"){kind=icon}
 "Boss Rush Apocalypse"){kind=icon}
 "Lionheart Tactics"){kind=icon}
 "Words are Hard"){kind=icon}
 "BroForce"){kind=icon}
 "Tap Heroes"){kind=icon}
 "Kana Warrior / かなウォリアー"){kind=icon}
 "The Enchanted Cave 2"){kind=icon}
 "bit Dungeon"){kind=icon}
 "Notorious Inc"){kind=icon}
 "Thrones of Fantasy"){kind=icon}
 "Puzzle Legends"){kind=icon}
 "Mighty Knight"){kind=icon}
 "Wartune"){kind=icon}
Kana drawing sounds fun, but there are too many different typefaces and that makes it difficult to recognize a kana (if you draw a き, how does the game determine whether it is correct?). Besides, it's a better idea to write kana on paper anyway.