I emailed him to ask, but it bounced back.

I've also emailed a few Chinese and Japanese guys to ask for Kanji.

By the way an American might still want their name umlaut'ed. I'm not concerned with why. I'll put it the way they want it. My ex was American with a French surname without diacritics, but she started putting an acute accent on the final 'e' after I started writing her name like that.