Synopsis: The Special Case Investigation Division of the National Police Agency is an elite department dedicated to taking in cases that "can't be solved." On his first day, rookie Naoki Yoshizawa discovers that there's no passion or justice here, only a peculiar detective, Shuhei Akechi, exiled for "solving too many cases." Akechi's solve rate is 100 percent, but every case he solves is a "botched crime." A locked-room murder: the killer carefully planned a perfect trick, only for an unexpected earthquake to bring down the ceiling and expose them. A copycat murder: the killer imitated the nursery rhyme from And Then There Were None, but got the lyrics in the wrong order, scrambling the victims' sequence. A perfect alibi: the killer calculated every second, but forgot that it was a leap day. Shuhei Akechi has a pathological fixation on these "imperfect crimes." He doesn't arrest criminals. He writes Reports on the Study of Failed Crimes, analyzing where the culprit "didn't try hard enough." Yoshizawa gradually realizes that an unseen hand seems to be manipulating these failed cases. Someone is deliberately making crimes imperfect, and Shuhei Akechi is the very "accomplice" helping them. Then one day, Akechi writes a single line in his report: "The 100th failure has been filed. Next is my own murder case."
