It's quite individual though. @_@; Bleaching is a lot worse than going dark. But it really depends on what quality your hair is. For example my mom's hair is very.. weak? idk. And bleaching it really harms it. Whereas mine is... damn strong and I have too much of it.
I bleached mine often for a few years when I was in junior high, and even then it didn't harm my hair much at all.
I'm sure Aichan's is okay.
Especially considering all the treatment you get at hair salons over here.