Great color palette. I really like what you have going on, but I think there are a few things holding this set back a bit.
As it's presented, the orange's purpose seems to be as an accent color. So with the dark bases with the gray and black, the choice to put hiragana in the base kit and making those sublegends orange too, all-in-all ended up making my eyes ache because there's a bit too much of that bright orange being pumped into the alphas and sublegends. I would've suggested using the black do add a bit more contrast in the alphas so it's a bit easier to look at. And then with the kitting, you're making people pay more if they want less, if they want the latin alphas instead of the hiragana sublegends.
Just my thoughts, but I hope your GB does well!