The First Investigation Division of the Metropolitan Police Department, which is based in the Dai-Tokyo Police Station , is headed by Keiichiro Funakoshi, the Chief of the First Investigation Division . This is a department that specializes in considerations that lead to solutions. Along with Ryu Fujii , a new detective who was newly assigned for some reason , they lead to the solution of many difficult cases one after another while colliding with each other's strengths.
Kosuge, the president of a factory, is killed by someone while returning home. A bag charm is found at the scene. When Akira Higuchi and his colleagues from the Metropolitan Police Department's Investigation Division investigate his home, they find a bankbook with the letters A, Y, M, and S written in English. It turns out that the charms left behind were custom-made by Seiji Iwai. However, Seiji had committed suicide five years ago in a robbery-suicide case. Seiji's mother, Mizuki, is an old acquaintance of Superintendent Tendo. Higuchi heads for Mizuki's place...
