[ Zenitsu stiffens at the question, his lips pursing shut as he thinks it over for a moment, eyes lowering to the ground in the mean time. ]

...Is it cliche to say that I actually want to get stronger? I whine and cry all the time. I can barely do much by myself, unlike my friends. I don't know how much stronger I can be, but... It'd be nice if I can get strong enough.

[ So that he doesn't keep disappointing people. At this point, he's not going to deny that he's never defeated a demon at all, but even with that he still feels weaker than his friends, especially in terms of having a strong will. ]