About 20 years ago, Nagumo Keiichirō was an ace detective in Japan despite being in high school. No case was too tough for him to solve. However, at 35 years old, his age is catching up with him. Nagumo no longer has the youthful energy or fame from his highschool days. Suffering from aching hips and back issues, on top of growing increasingly jaded, his private eye office is struggling to attract clients and making it hard to afford rent and food. But one day, an excitable highschool girl named Mashiro Nakanishi appears at his doorstep and wants to be his apprentice. Will Mashiro be the spark Nagumo needs to reclaim his passion for detective work, or invite further problems into his life?
