Comments called it bara, it's really not. Lots of different yaoi flavors though, from strangers to lovers, threesome senpai uke (2)/kouhai seme, gap moe, etc etc. I'm not sure I have a favorite, the way it surprised me just made for interesting reading.
Oh! I've read some of their work before, Brand New Star. Pretty sure I really liked that one.
Bachi Bachi (KIJIMA Hyougo)