Nisekoi follows high school students Raku Ichijo, the son of a leader in the yakuza faction Shuei-Gumi, and Chitoge Kirisaki, the daughter of a boss in a rival gang known as Beehive. They unexpectedly meet when Chitoge hops a wall and knees Raku in the face. After she runs off, Raku realizes he has lost his locket which was given to him by his childhood sweetheart with whom he made a secret promise. After discovering Chitoge is a new transfer student in his class, he forces her to help him look for the locket. During the search, they begin to dislike each other. Upon returning home, Raku learns that the Shuei-Gumi and Beehive gangs have agreed to settle their feud by pairing their leaders' children. Raku learns that his girlfriend-to-be is none other than Chitoge. For the next three years, they must pretend to be in a relationship to maintain peace between the gangs. This turns out to be quite a challenging task, not only because of their hatred for one another, but also because Raku has a crush on another schoolmate, Kosaki Onodera, whom he secretly wishes was the girl who bears the key to his locket. Various developments complicate the situation, including Chitoge's over-protective bodyguard, a female hitman, a girl who claims to be Raku's fiancée, and the existence of multiple keys.
Now that Chitoge has come to terms with her feelings for Raku, she sets out to mold him into the ideal boyfriend! However, with Raku being the oblivious guy he is, just how many different ways can Chitoge try to get him to recognize her more?
Tsugumi has a visitor from her past. Her dark, violent past… Now, she has to prove that she still has the skills she once had!
Christmas is just around the corner... Shu tells the gang that they should throw a party. However, Chitoge has other plans. Her mom is coming to visit, and Chitoge's dad wants to introduce Raku to her!
Raku is working extra hard as Ms. Hana's secretary in order to give her some time to spend Christmas Eve with Chitoge. However, is Ms. Hana really interested in getting together with her daughter?
Marika asks Raku to help her study, since her grades are very low. Raku agrees to tutor her, but Chitoge wants to tag along! Also, now Raku is given a pet he needs to take care of!
It's Valentine's Day and Raku dreads the idea of not receiving chocolate from anyone. Meanwhile, Chitoge, Kosaki, Marika, and Seishirou are all dealing with their own issues with what giving chocolate to someone entails.
Kosaki's younger sister, Haru, finally enters high school. After hearing unsavory rumors about Raku, Haru is none too pleased about him trying to get close to her sister.
Kosaki, Marika and Chitoge work together as magical girls to save the world from destruction. As Ichijou pitches in to help at the Onoderas' shop, Kosaki hopes he and Haru can become good friends.
Raku pays a visit to Kosaki, since she has a cold. However, is it appropriate for a guy like him to go see a girl when her parents are out of town? What does Haru have to say about the situation?
Suspecting something is up, Raku asks Shu which girl he is crushing on. Will Raku be able to get the truth out of him?
Haru points out that Kosaki has been enjoying sweets a lot lately. After getting on the scale, Kosaki decides that it is time to lose some extra weight. Will she be able to control her irresistible hunger and turn her back to the haunting temptation?
Chitoge wants to tell Raku how she feels about him, but she is scared of rejection. Will she manage to gather some courage?