As it is, this app is pretty spectacular. It’s simple, it fits the bill for quick review of the kana, and it does everything it’s supposed to do. I have one qualm with the UI. Getting to the settings isn’t exactly intuitive. I love how it’s done, but a single page tutorial explaining how to access settings for first time users would go a long way.
As a feature request, I think using spaced repetition (see wikipedia Spaced_repetition) would take this to the next level, and then voice recognition would be incredible. That would help with those of us who know the kana and want to speak as much as possible (I say them out loud when I read them). But, keep in mind, this is a lot to ask for. The developer(s) did a really great job!
(The missing 5th start is just for the lack of obvious way to adjust the settings.)
gluis about Real Kana