Once a legendary detective, Nagumo Keiichirou now stumbles through middle age baffled by smartphones and modern life. His quiet decline gets disrupted when Mashiro, a bold high school girl, bursts into his office demanding to become his apprentice. Though he's rusty and set in his ways, her relentless enthusiasm drags him back into detective work. Now the gap-bridging detective duo is on the case!

[Source: Crunchyroll]