Ino-Head Gargoyle (井の頭〈イノヘッド〉ガーゴイル Inokashira Gargoyle) is a 5 volume spin-off of GTO manga that was published from January 16th, 2012 to January 20th, 2014, total of 39 chapters.
Known as the gargoyle of Inokashira Park police station because of his scary face, Saejima Toshiyuki was a loser. He's pretty much a virgin for all intent and purposes, aside from the companions that he pays for. He wasn't always a loser though.
During his high school days, he was feared as a badass, but now he is just a person people feel sorry for. He then meets Arimori Shizuka, a beautiful girl that seems comfortable in her sexuality. Toshiyuki learns that she was a high class escort that has been with over 1000 men.
She was doing it out of love for her abusive boyfriend but, realizing her mistake, quits. Shizuka is now being harassed and Toshiyuki reverts back to his aggressive personality to protect the love of his life.