世間を騒がす難事件を即解決！ その名は名探偵・名雲桂一郎!! だったのは10年以上も昔の話……。
名雲はいまや、ただの渋いおっさんになってしまった……。時代に取り残され、スマホすら扱えない彼のもとに、若さあふれる女子高生・真白が助手希望で押しかけてきて――!?
Nagumo Keiichirou was a genius high-school detective. No case was complex enough for him. But what happens to genius detectives when they get older? Now 35, with bad hips, running a failing detective agency with no cases to solve and struggling to pay the rent, he’s at a dead end. In comes a high school girl in his office who says she wants to work with him. With her help, will the out-of-touch, old-fashioned Nagumo get back the fire of his youth?
