Tsugumi, Seishirou

Tsugumi is a hitwoman who was raised and trained by Claude of the Beehive Gangsters.Tsugumi is originally introduced as a guy who transfers to Chitoge's class, and has orders to protect her from Raku, whom she thinks forced Chitoge into the relationship. She and Chitoge are childhood friends; she tries to keep a ten year old promise of becoming strong to protect Chitoge. However, after Raku treats her nicely, she begins to develop some feelings for him, even though she is too stubborn and embarrassed to admit it. In America, her assassin code name is "Black Tiger," who had a rivalry with "White Fang." She does well academically, having ranked next to Chitoge on a yearly exam.

Later when she learns that Chitoge and Raku had been having a fake relationship from the start for the reason of only to stop their families from fighting. She investigates their individual feelings for each other to know if she has a chance. She comes to the conclusion to give up in order for Chitoge to be happy and one day when alone with Raku in the classroom, she places her hands over his ears and confesses her love so that he doesn't hear it. She later helps Chitoge and Raku come to terms to their mutual feelings.

In the epilogue, she becomes Chitoge's exclusive model.

(Source: Wikipedia)