http://allthetropes.wikia.com/wiki/Build_Tiger

"Build Tiger (ビルドタイガー Birudo-Taigā) is a homoerotic Bara Genre/Comedy Kemono Doujin written by the artist Gamma (who was also part of the Morenatsu Project).

The story: The titular character is an everyday human male named Entaro, who is also a self-proclaimed hero of Justice. With the help of the brilliant yet perverted tiger scientist named Professor Buttertoast, he fights the organization known as Dragon Mafia Co. Using a special collar, he turns into the superhero known as Build Tiger (BT for short). Unfortunately, most of the time he usually ends up some other anthro male's bitch, something of which he isn't particularly proud. Thus, Hilarity Ensues."