If it weren't for the fact that Mina hails from a hentai, she would probably be in my top ten, but since the show (and game) she's from is titled "Sex Friend," she'll have to deal with being on top in this section only. My first experience with Mina was when I got the chance to see a few CG's from the game she stars in, and it was some of the most beautiful artwork I'd yet seen in a game of that sort. (I'd post more pics from it here but yeah... not exactly PG :P) I haven't seen anything since that compares really, but I was forced to look for the animated OVA and watch it, it was the first hentai I'd watched. As the title suggests, it's basically about two high school kids who are "friends with benefits," an ambiguous relationship to begin with, but it really feels like there's a developing love. Mina is a fairly simple character, a cute & sexy girl who's pretty randy, and has a bit of personality. She teases a little, but is open-minded and forgiving. (except with her old boyfriend at the beginning of the show... I dunno what he did, but ouch, he got dumped HARD) Anyway, Mina is definitely a harem kind of girl. ;)
