The Entrusted Bones, Part 1.Sakurako comes to Shōtarō's school for their culture festival, with Shōtarō's class running a maid café. After voicing some complaints about the animal skeletons set up in the lab, Sakurako is asked by Isozaki to sort through some bones in the science prep room. While doing so, Sakurako explains how she made her first specimen from her dead cat, her indifference to which doesn't settle well with Shōtarō. They soon come across a chest containing cremated human bones, belonging to a girl named Natsuko Sono who was close to the old science teacher Atsurou Sasaki. The next day, after the police go through the discovered bones, Shōtarō discovers a bunch of cat bones have gone missing, suspecting Sakurako. Meanwhile, Sakurako visits a hospitalized professor named Shitara Masamichi and decides to investigate an unsolved case.