Yagi to Ookami no Hatsujou Jijou

From Yaoi Sekai:

“To me, you’re also a woman.”
A cocky sadist with dual personality “Goat” and a head-strong delinquent “Wolf”. One’s unstoppable when his mating period kicks in! Today, he’s in for sex even if it’s by force! And the other one’s too lewd for a beast that even a woman would be put to shame!?

A planet called Serian, which believes to be a twin of Earth, is where human beasts Yagi and Okami live. They both entered high school and was sent out to an infiltration training together. They were once close with each other but now, there’s nothing but fights between them whenever they open their mouths.

The story starts three days after they’ve arrived on earth prescribed with human shifting medicines and mating prevention pills. Incidentally, Yagi got into his period but his reactions were weird… Worried, Okami tried to talk it out with him but got pulled in and got his nape bitten!?