With the release of My Hero Academia: Vigilantes episode 4, the anime saw Kuin Hachisuka speak to her boss and make her move. Additionally, the anime episode saw Ingenium form a good relationship with Crawler after the hero and vigilante assist each other.
The anime's previous episode saw one of Pop's fans inject himself with Trigger, hoping to shake her hand. Fortunately, the vigilantes stopped him in time. The anime later saw the series' antagonist Kuin Hachisuka make her first appearance, as the part-time villain launched her Trigger-equipped bees on the city.
My Hero Academia: Vigilantes episode 4 - Ingenium learns the Crawler's identity

My Hero Academia: Vigilantes episode 4, titled Top Runner, opened with the three vigilantes again stopping a group of criminals. This is when it was revealed that Knuckleduster wasn't feeling himself since he failed to track down the bee user. The anime later saw Knuckleduster training Koichi. While Koichi tried to speak with him, Knuckleduster did not want to reveal what was bothering him.
The anime then switched to Kuin Hachisuka as her boss told her not to waste Trigger and only use it on people who could pull the trigger with their own will. Kuin Hachisuka did just that as she unleashed a new Instant Villain onto the city. Fortunately, the vigilante managed to secure the location. As for Knuckleduster, he fought the villain one-on-one and defeated him. With that, Knuckleduster was back to his normal self.

The anime episode then saw Knuckleduster happily training with Koichi the next day. Elsewhere, Kuin asked her boss what she needed to do about the vigilantes. Surprisingly, the boss wished to use them to gather data on the drug without any interruptions from the heroes. The anime then saw Kuin meeting up with an office worker for what looked like a blind date.
My Hero Academia: Vigilantes episode 4 then switched its focus to Ingenium as he was pursuing a villain causing trouble on the highway. Unfortunately, despite his speed, he could not stop the villain.

The next day, Koichi Haimawari stumbled upon Tensei Iida during his morning "slide" training. Upon witnessing Koichi's Quirk, Tensei Iida suggested that he try moving the opposite way whenever he wished to stop while sliding. This suggestion worked wonders for Koichi as he could finally stop while sliding fast. Additionally, Tensei handed Koichi Idaten's card, asking him to join his support team and work his way towards a hero license.
The anime then switched to another day as Ingenium and his Idaten team again chased after the villain from before. While the hero had perfectly planned everything, the villain's bat-like flying ability was a surprise. Hence, the Idaten team had trouble locating the villain. That's when Knuckleduster and the Crawler stopped the villain. Ingenium immediately recognized Koichi when he saw him in his Crawler outfit.

The next day, Tensei Iida again met Koichi during his morning run. This time, he asked Koichi for his card back, as he believed that if Koichi had already found a place for himself, there was no point in recruiting him as part of his team. This development left Koichi saddened.
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