Hitotsubana 

A secret first love with his long admired senpai. Even if it didn't bear fruit, it still became a cherished sweet and sour memory for him, or at least that's what should have happened. "I want to make you mine at any cost." This warped affection in the boy's heart continued to blossom a pitch black. The faint love he held dear to his heart, eventually transformed into something else entirely... With their endless cycle of love and hate, and toying with each other's hearts, exactly where will this boy and girl end up!?