Hiragana Battle is language learning game hobbled by the limitation of the RPGmaker system more than anything else. It's a noble effort, but system mechanics get in the way of being an exceptional and effective learning system.
The way this game works is that if gives you 5 (usually 10 actually) Hiragana letters per lesson and uses those letters as monsters to battle NES Final Fantasy style. Where you need to have each character select from the menu of learned options and pick the correct one to deal damage based on the character's strength and weapon. As you learn more hiragana, this menu becomes quite cumbersome.
Additionally, the player has to gauge how much health of the 'hiragana warrior' has vs. the damage each character inflicts. Because a character targeting a defeated warrior will just attack the next one. And is almost never the correct letter. Thus a wasted attack.
Honestly, I think a game like this would work better more like the original Dragon Quest/Warrior game. With only a single character. I found myself lower areas trying to get more practice to familiarize myself with earlier hiragana only needing a couple of the characters to attack to defeat all the hiragana warriors. Yet, I had to navigate the menu for the whole party.
Fortunately, the game does have each character stay on the previous option they picked. Which is handy when the player miss judges the amount of damage needed. As well as each area tends to focus on a particular group of hiragana.
The game part is standard turn-based RPGmaker fair. The music is nice. The characters and gear are bare-bones. Which feels more like a feature to focus on the educational aspect. The game developers did a good job fitting the square peg of of learning hiragana into the round hole of RPGmaker. But it is clear the the limitations of that don't offer more effective learning than flashcards.
Which is where I ultimately can't recommend this game. If you enjoy retro turn-based CRPGs and want to learn hiragana, this game is okay. If you just want to learn hiragana. Just make some flashcards instead. I think your progress will be much faster.
Learn Japanese To Survive - Hiragana Battle is a good effort, but is too limited by mechanics to be a highly effective learning game.