Tasuku Mitomo is a natural-born assistant, a helper-type personality that compels him to lend a hand to anyone in need. This tendency has always kept him in the shadows, lived in the wake of others. Determined to change his fate, he sets one goal above all: become number one. When he transfers to a new high school, he crosses paths with three detective girls: Hiyori Akechi, Touka Aruse, and Ritsu Iezumi. These girls are no strangers. In elementary school, they formed a detective club together, and now they are his rivals for the top detective spot. Tasuku throws himself into a fierce battle to support the top detectives and claim the title for himself. But the girls harbor a different kind of passion. Their feelings for him go beyond rivalry and into romance, creating a sweet and competitive love quadrangle. As the story unfolds, the four of them run a detective club at school, solving cases and navigating their tangled emotions. Touka makes the first direct confession, pulling ahead in the race. Tasuku hesitates, unsure of his true feelings. The girls resort to hypnosis to learn his heart. Ritsu also confesses, and Tasuku begins to see all three as romantic interests. Their affections escalate, and a reunion with a girl from his middle school past adds a new complication. The series follows their gentle, competitive relationship to a conclusion, where the triangular love and detective rivalry find their resolution.