Gaiden Chapter 4

Department of Justice Main Building / Morning / Sunny ① (司法省本館／朝／晴天 ①,) is the first part of the 4th chapter of the Bungo Stray Dogs Gaiden manga.

Summary
After the incident that claimed the lives of the special forces, Tsujimura meets Ayatsuji in front of the Department of Justice Main Building for her testimony. According to Tsujimura, murder by ability is quite difficult to handle; after all, the Special Division for Unusual Powers manages ability users, and one of their agents killing others – let alone members of the special forces – using an ability can be considered as abuse of public authority. Moreover, adversaries of the Special Division might elevate such incident into a scandal.

As Tsujimura becomes anxious, Ayatsuji tells her not to expect him saying that she "only made a natural, rookie mistake" and to "be careful next time", as he claims that there is no next time in matters regarding life and death. Tsujimura then muses on her ability, which does not follow her orders and which she knows almost nothing about.

She then asks Ayatsuji if he ever considered thinking to be better off without his ability, but he merely asks her when her ability awakened. Tsujimura recalls five years ago when her mother died in the Reigo Island Seventeen-Victim Massacre; Ayatsuji surmises that her ability's origins might have something to do with such incident.

In the massacre, visitors disappeared after arriving on the island including her mother, after which Tsujimura received her ability. The Special Division then scouted her shortly afterwards, with Ango telling her to consider it a "gift" from her mother, whom she had an estranged relationship with. Tsujimura asks Ayatsuji whether he was able to solve the incident, but he denies having information about it.

He does expound that he pretended to live in the island in order to find the culprit. There were 17 island residents who were killed and the 18th resident was the mastermind. The suspect was known to be a male, had a partially-cut ring finger, and incited the residents to cause the serial murders. In the end, the 17 residents died of "accidents" due to Ayatsuji's arrival and ability, while the 18th person, codenamed the "Engineer", was not in the island when Ayatsuji arrived and thus was never found.

Tsujimura then considers such event to be of utmost relevance to her, Ayatsuji, and the Engineer. Ayatsuji soon asks Tsujimura whether she joined the Special Division and became his supervisor in order to exact revenge regarding the island massacre.

Characters in Order of Appearance

 * Mizuki Tsujimura
 * Yukito Ayatsuji
 * Ango Sakaguchi (flashback)
 * Santōka Taneda (cameo)
 * Tsujimura's Mother (flashback)
 * Engineer (partial cameo)

Abilities

 * Yesterday's Shadow Tag (flashback)
 * Another (offscreen; flashback)