User blog comment:Theluckysakura/Kuro Kiku/@comment-1151277-20100829200544

"Kiku Honda" is the human name that was assigned to Japan.

I'd imagine that "Koru Kiku" is the result of some fan-trend or fan-creation, because I don't recall Japan dressing that way anywhere in the canon :/

EDIT: Okay, he HAS dressed like that in the canon - Uniform Guide: Japan - But I don't know where the name "Kuro" came from.