This special episode is a spin-off of Galileo series with Kusanagi's colleague Yuge Shiro as the main character about an incident referenced in the first episode 01 and how it was solved. It is set 3 years prior to the events of season 1.

The special is set 3 years prior to the drama series, with the story being related to a murder case that was partly referenced in the original show. Detective Kusanagi is looking to solve a murder mystery, and he gets back in touch with his former badminton teammate, the brilliant professor Yukawa Manabu.

Four years before Silent Parade (2022), Yukawa and Kusanagi investigate the murder of a writer after a video found in his possession piques Yukawa's interest.