Duel

is the sixteenth chapter of the Nisekoi manga series written and illustrated by Naoshi Komi, published weekly in the magazine Weekly Shōnen Jump.

Summary
Chitoge interrupts Tsugumi and Raku and tries to calm them down. Tsugumi tells Chitoge he can’t accept Raku as her partner and asks her if she remembered the promise they made ten years ago. The promise pushed him to become stronger to protect her, while seeing Chitoge with a weaker man is something he cannot accept. He challenges Raku to a duel after class in the school yard and promptly leaves. Chitoge explains to Raku that Tsugumi was an orphan, taken in, and raised by Claude with special training and education; turning him into an exceptional hit man. Raku felt he is getting in the way between Tsugumi and Chitoge, after reflecting on the situation. Chitoge then whispers to Raku not to lose.

A crowd has gathered at the meeting place of the duel. The duel will start as soon as a coin hits the ground. Tsugumi flips the coin and pulls out an arsenal of guns from his uniform. Raku reacts to this and sprints into the school.

While running through the school’s hallways, Tsugumi continues to shout how he will be the one to protect Chitoge. Raku states that Tsugumi doesn't understand Chitoge at all, since she is the kind of person who doesn't sit around to be protected and if he is a real man, he would grow up and watch over her. Tsugumi, clearly upset over not being called a man, chases even faster. Raku then jumps out of the window as he follows. The two fall into the school swimming pool, with the impact knocking Tsugumi unconscious.

Raku, fearing both of them will catch a cold if they stay out with wet clothes, carries Tsugumi into the boy’s locker room. As he was in the middle of taking off Tsugumi’s top, Tsugumi wakes up with a scared impression on his face, his open shirt exposing a bra. It then dawns on Raku that Tsugumi is actually a girl.

Character Revelation

 * Tsugumi and Chitoge made a promise with each other ten years ago.
 * Tsugumi is adopted and trained by Claude to become an exceptional hit man.
 * Tsugumi is actually a girl.

Trivia

 * This chapter was as pated into an episode for Rival (episode).