My username rhymes with my actual name, and I guess I was having fun when I first made the name?
Anyways, I first used it on GBAtemp (a Nintendo-related forum) in 2009, and has since been my go-to name for cutesy and/or light-hearted games (and eventually, pretty much every game).
But recently, I've actually started to grow attached to the Japanese name 拓海 (takumi, translates into "open sea"), and have been using it for some VNs (voice-acted or otherwise) that require you to input a character name. There have been times where I felt the name "YayMii" was unfitting for the type of person I was, but other people have helped me realize that I was just being melodramatic and overly depressed... I'm past that now, but I still would not mind renaming myself to TakuMii if it weren't for the fact that other people have expressed a liking to my username