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...
Saeki, a doctor at a small local clinic, receives a visit from Sayaka, the younger sister of his late friend, who informs him about her wedding. However, a few days later, Sayaka is found suspiciously dead inside her own apartment with a white ribbon wrapped around her neck!
