Does finding characters who use risky powers that eat away at the user's soul appealing make me chuunibyou?

"No."

Makes it even better. Heroes that have a sacrifical power and actually have consequences for using it make me diamonds. Even better if they have an enrage/demon/monster mode. It's a shame most media that uses it only have the consequences as backstory or the ending before it ends happily ever after.

Yes. If you wanna go with the "sacrifice something for power" at least make it interesting.
I have played with a PC that would sacrifice memories to empower spells. Which meant that in game terms he would lose xp and character wise he would forget skills (forget how to write as an example). It had way more impact since it was a part of himself he burned away rather than something as vague as his "soul".

Depends on if you run around thinking you are your character or not. Also kind of depends on the sacrifice.

you made me go and look up that word, but once i had looked it up, i became pretty certain that you don't know what it means either.

It only makes you chuuni if you're a nip, 13-16 years old, and you actually believe your character is you.

>thinking you can understand 40+ years of subculture with the definition of a single word

OP is braindead and still knows more than you.

What if there are demonstrably harmful and hindering effects resulting from soul decay? A la corruption in Symbaroum.

Like a Prince Ashitaka's curse sort of idea.

Except with an unhappy ending.

"I'm getting awfully tired of this curse, Ashitaka. Why don't we just cut the damn thing OFF?!"

I like you.

I actually find that there aren't a whole lot of systems that let me play this sort of character in-depth. It's one of the reasons that I've started growing a dislike for D&D lately.