Idols Keep Their Secrets! (アイドルには秘密があんねん! Aidoru ni wa Himitsu ga An Nen!?) is the thirty-second chapter of Hideyuki Furuhashi and Betten Court's Vigilante - My Hero Academia: Illegals.
Summary
Monika riding a Mech
The chapter begins with Kazuho interpreting the theme of Marukane Department Store in the Idol Show. When her turn ends, she and Koichi decide to see the exhibitors and the souvenir shops of the venue. As they walk, they find Monika riding a crab-shaped Mech.
His manager explains to the surprised Koichi and Kazuho that they had remodeled the industrial lifting arms into Walking Advertisement. A person arrives and tells Monika to get ready, because soon it's her turn to go on stage. She goes to the place with the mecha, but suddenly she apologizes to her manager because she needs to go to the restroom. After her departure, the manager looks at his watch, and then at Koichi and Kazuho.
Back to Naruhata, Shota Aizawa chases the Hotta Brothers, two minor dealers. After Aizawa cuts off their route of retreat, Jiro and Ichiro decide to use Trigger, transforming themselves into humanoid insects, and attack Eraser Head.
Nemuri convinces Shota to help Naomasa.
The fight is cut to show us a flashback where Aizawa speaks with Detective Naomasa, who asks him for help with his investigation of the Villain Factory, which is what the police call the mysterious organization that is behind the kidnappings of people to transform them into Next-Level Villains. At first, Eraser Head is not very sure of participating, because act as a detective is not his thing, but Nemuri Kayama convinces him to help the police.
Shota talking with the Hotta Brothers
Back to the present, the Hotta Brothers are defeated and wrapped in Aizawa’s Capturing Weapon. He tells them that he is not a policeman, and that he will overlook their fight and the fact that they used Trigger if they give him information. The Hotta brothers say he will get nothing, but when Aizawa shows them a photo of a person and his mantis form, the two brothers immediately recognize him as his friend Kirihito.
The Hotta Brothers take Aizawa to their shop to continue speaking. The Hotta are surprised about the latest events of his friend and his transformation into Next-Level Villain. They attribute what happened to Kirihito is because he was involved with the traffic of Bad Trigger, because has uppers mixed in and made people rampage. They told Kirihito to not get involved with it, but he ignored their warnings.
Naomasa asks Monika to be careful
They assure Aizawa that they sell legal Trigger, to help stop balding and erectile dysfunction. Aizawa tells them that he doubts they have any license to sell the stuff, although he decides to ignore their excuses whenever they gives him all the information they knows about the traffic of Bad Trigger. Also, he asks them if they know anything about the crab route.
Back with Monika, it is discovered that she is not a Kanidoge's employee but a covert police who works with Naomasa and Fat Gum in the operation to dismantle the traffic of a batch of Trigger. While talking to Fat Gum in a friendly way with the ear piece, Naomasa informs her that Kanidoge's already started unloading its farm-to-table products at the mall's service entrance.
As soon as she can confirm that there are drugs disguised in food packaging, they'll move in for the takedown. Until then, she’s on her own out there, so he asks her to don't take any unnecessary risks.