In the world of sixth-grader Aya Tachibana, concerns about friendships, family, and academics consume her thoughts. Her life takes a turn when she teams up with four quirky boys from her cram school to form the 'Tantei Team KZ.' Led by the charismatic Kazuomi Wakatake, the team includes the enigmatic relationship expert Takakazu Kuroki, the brilliant mathematician Kazunori Uesugi, and the kind-hearted Kazuhiko Kozuka. Aya, known for her linguistic prowess, complements the group. Together, they tackle contemporary mysteries, leveraging their unique abilities to crack intricate cases despite occasional disagreements.