The detective with the highest arrest rate. In fact, he was a vicious detective who communicated with the gangsters!

Absent-minded fifth-grader Yuta is sent to spend the summer with his grandfather, whom Yuta's parents think is becoming senile and could benefit from Yuta's companionship. At first, Yuta thinks Gramps is a bit addled, too, but as he gets to know the old man better, he finds that his grandfather sees things quite differently from others.