It's not weird. [ he's sure there are lots of people with one piercing, though he'll admit that there are some connotations to it. he doesn't bother explaining them, though. ]

I can do it later. I'd just need a piercing needle.

[ he watches naoto continue dying her own hair, not making any attempt to help her make it look good until she seems almost done. ]

...you sure you want to do it like this?