Kenji is a motorcyclist enthusiast who loves nothing more than to ride around on his motorcycle. He invites Tomomi on a tour of Hakone, but by doing so is introduced to a car driver named "Wednesday's Cinderella", whose Porsche is supposedly haunted by the "devil". Motorcyclists show up every week to try and compete against the driver, but none of them ever win.
Kenji sees this as a challenge and asks a bike shop owner to tune his bike for the purpose of competing against this driver, just for pure fun. The bike shop owner refuses due to past trauma that gets triggered upon the sight of his bike (and due to trauma that the Cinderella driver has), but eventually does so anyway, in the hopes that Kenji can cure the Cinderella driver's trauma by winning.

Aitsu to Lullaby: Suiyoubi no Cinderella