The story follows Kouta, a high school student who works part-time to support himself. One day, Chris, a beautiful celebrity girl claiming to be his fiancée, suddenly appears before him. Kouta soon learns that his father, who was blinded by money, entered into a marriage contract with Chris without his permission 10 years ago. Determined to take control of their own lives, Kouta and Chris form an "Engagement Breakup Alliance." However, Kouta soon realizes that Chris has an ulterior motive: she wants to use Kouta to win back her first love. To help her achieve this goal, Chris suggests that Kouta should pretend to have anew fiancée to make her former lover jealous. Kouta agrees but shocks Chris by revealing that he already has a girlfriend.

This revelation sets off a love triangle that forms the backbone of the story. As Kouta and Chris work together to find Kouta's new fiancée, they become closer and their feelings for each other begin to grow. Meanwhile, Kouta's girlfriend becomes jealous of Chris and tries to win back Kouta's affection.

The light novel is a fun, light-hearted romantic comedy that keeps the reader engaged with its humor and relatable characters. The love triangle aspect of the story is well-executed, with each character having their own unique personality and motivations. Kouta is a likeable protagonist, with his earnestness and hard-working attitude winning over the reader. Chris is a fascinating character, with her beauty and charm masking her true intentions. Kouta's girlfriend is also well-written, with her jealousy and insecurity adding a layer of complexity to the story.

The writing style of Misaki Nagi is engaging and easy to read, making the novel accessible to readers of all ages. The pacing of the story is also well-balanced, with the plot moving at a brisk pace while still allowing for character development and emotional moments. The illustrations by Kuroto Yuu are beautiful, adding to the overall enjoyment of the story.