Broken Spiral

Broken Spiral is a light novel sequel to Broken Minds.

Official Synopsis
Kuroyo Kage is a member of the police, who secretly works for the YPDA. When Reiwa Kyougi stupidly instigates a police investigation into Uzumaki's death, things get ugly, and Kuroyo is forced to take drastic steps to protect them. Along the way, new details emerge about the YPDA, Uzumaki, and Noa as the narrative jumps in time between 1992 and 1993.

Status
Available along with a purchase of Broken Minds on Steam, itch.io and GameJolt.

Characters
Kuroyo Kage

Tsukune Fujinoya

Reiwa Kyougi

Yuzuki Hiiro

Ume Hakase

Takuma Karashi

Hoshi Watamoto

Officer Sugimoto

Maaka Umigami

Locations

 * YPDA offices
 * YPD headquarters
 * Fujinoya's Dating Service

Plot
SPOILER WARNING! The full plot of the light novel is laid out below. Proceed with caution.

In 1993, Reiwa Kyougi reports Uzumaki's murder to the Yamagata Police Department, because she's afraid Noa will try to kill her next. She clues the police in on the YPDA's involvement. However, Kuroyo Kage, a double agent, is a member of the team sent to investigate.

Back in 1992, during the mystery cram, Kuroyo investigates Dr. Uzumaki's house, and only discovers unexchanged pachinko tokens. She decides to investigate the hospital, while the detectives break into Noa's apartment.

1993: During their investigation of Uzumaki's offices, which have been turned into the headquarters of a dating service, Kuroyo discovers evidence of the detective's autopsy in the bathroom. Instead of hiding it, she lets Hoshi, the chief investigator on this case, see it and draw his own conclusions.

It turns out that Yuzuki left a fingerprint in Uzumaki's bathroom. This makes Kuroyo panic about them finally being caught. She goes in person to the YPDA offices to convince them to get rid of evidence, but unfortunately does so right when Hoshi decides to show up.

He investigates their offices, and finds nothing. However, he does overhear Kuroyo talking to the detectives and realizes she's a spy.

As they drive back to the station in the pouring rain, Hoshi convinces Kuroyo to join his side and betray the detectives in order to finally bring them down, trusting her not only because of the amount of time she's spent on the force, but because she reveals a secret that only the YPDA knows about her.

Hoshi is impatient and quickly assembles a task force and plans a raid of their offices. However, the raid is called off after Takuma unexpectedly saves someone during a flood.

Kuroyo finally convinces them to get rid of the evidence they've been keeping in the office, and Ume even deletes data from her laptop.

The raid is carried out, but, of course, no evidence is found. The detectives get a bit cocky and bribe two of the task force members to not bother investigating them anymore, right in front of Hoshi, just because they can.

Hoshi realizes just how powerful the YPDA is, and leaves, defeated, at least for the moment.

Kuroyo calms herself from all the recent excitement by stalking an old target.