There was once a brilliant detective who built a dazzling legacy and basked in fame.
No case was too tough! No mystery unsolvable!
That high school detective’s name was Keiichiro Nagumo!
...But that was more than ten years ago.
Now? He’s plagued by back pain, farsightedness, and sensitive teeth.
What’s a "smaho"? What’s a "JK"?
The once-glorious teen detective is now a middle-aged man left behind by the times.
“It’s not that I’ve lost my talent. I’ve just lost a bit of my youth.”
Then one day, a bubbly high school girl named Mashiro barges into the Nagumo Detective Agency, insisting she wants to be his assistant.
Apparently, she dreams of becoming a detective herself...!?
Thus begins a heart-pounding (and maybe heart-straining) everyday life between a grizzled old detective and a self-proclaimed quirky-cute JK assistant!