Chapter 42 (Vigilantes)

Koichi joins Akira, Hiroto and Daiki of the Mad Hatters at a mixer with four sophomores from Naruhata Women's College, who give their names as Rin, Hina, Kaori and Kazuha. Drinks and small talk follow, with Koichi conspicuously out of his depth. Kaori excuses herself to touch up her makeup and takes Kazuha along, and in the restroom the disguises come off: Kazuha is Kazuho Haneyama and Kaori is Midnight.

The invitation reached Koichi because the Mad Hatters' leader refused to attend, unwilling to feel disloyal to the girl he loves. Koichi said yes, to Kazuho's disgust, and she was tailing him to the venue when Midnight ran into her and recognized her as the Pop Step from the first Narufest.

Midnight's assignment is a ring distributing Trigger at mixers, typically run by whoever organizes them. With Rin Yaritezawa as the prime suspect and her friend Hina alongside her, Midnight rings the Midnight Boys and has them draw off the two women who were meant to fill out the party, then slots herself and Kazuho in as substitutes. A flashback shows the case first landing with Shota Aizawa via Naomasa Tsukauchi, and Aizawa turning it down as too high-energy for his taste while pointing Naomasa toward Midnight instead.

The band members are cleared, Midnight tells Kazuho, since they know them from Narufest, which narrows the field to Rin and Hina. Kazuho draws Hina's attention while Midnight watches Rin, and back at the table Kazuha learns that Hina counts among Rin's friends and never leaves her side. Rin, meanwhile, is souring on the whole evening: a band she thinks little of, an awkward Koichi, two strangers she never met, and Kaori running the show. She stands to leave, collapses, and is sick on the floor. Koichi hurries over to help and she is moved by the concern. Hina grabs the towel used to clean it up, flees to the bathroom, and licks it, wild with jealousy at everyone fussing over Rin and at Koichi most of all, and reaches for some Trigger.

Koichi attends a mixer with the Mad Hatters, where Midnight and Kazuho Haneyama are working undercover as Kaori and Kazuha.

Midnight's target is a Trigger distribution ring operating through mixers, with Rin Yaritezawa as the chief suspect.

The case is revealed to have been offered to Shota Aizawa first, who passed it to Midnight.

Rin collapses and is sick, and Koichi's concern for her sends Hina into a jealous spiral.

Hina prepares to use Trigger.

Written by Hideyuki Furuhashi and illustrated by Betten Court, the chapter runs nineteen pages, published November 24, 2018 and collected in volume 6 of My Hero Academia: Vigilantes as part of the Team Ups arc. Episode 18 of the Vigilantes anime adapts it. Koichi Haimawari and the Mad Hatters appear on the cover, and both Rin Yaritezawa and Hina debut here.

The chapter's Japanese title first appeared in a shorter form and was amended for its volume printing.