Kobayashi, a bored middle school boy, wakes up in his classroom to find his teacher murdered, the murder weapon (a saw) in his hand. With the help of Akechi, a high school detective, he attempts to prove his innocence.
Kobayashi and Akechi unravel who committed the murder of the former's teacher, after learning that the teacher had previously turned his lovers into chairs.
A kidnapper is stealing away young girls and Akechi's on the case, aided (or perhaps hindered) by Kobayashi. However, what does the elusive Shadow Man have to do with this case?