Gleipnir 9

Dark, disturbing, and sexy, this sci-fi action manga that inspired the new anime stars a dominating teenage girl searching for a sister who became a monster, and a submissive boy with the strange power to turn into a ragged but powerful beast, with a zipper down his back and a compartment on the inside just big enough to hold a human body.
Shuichi Kagaya an ordinary high school kid in a boring little town. But when a beautiful classmate is caught in a warehouse fire, he discovers a mysterious power: He can transform into a furry dog with an oversized revolver and a zipper down his back. He saves the girl's life, sharing his secret with her. But she's searching for the sister who killed her family, and she doesn't care how degrading it gets: She will use Shuichi to accomplish her mission...
Story Locale: Present-day Japan