At the orientation for U.A. High's second term, Nezu mentions the Hero Work-Studies that upperclassmen participate in. Confused, Class 1-A inquires about it in their first homeroom class of the new semester. Shota Aizawa, their homeroom teacher, only gives his class a small description of how Work-Studies are a more advanced form of the Hero Office Internships Class 1-A participated in the last term.
Ochaco Uraraka frantically asks why the class had bothered working hard in the U.A. Sports Festival if they were going to get scouted anyway. Shota replies that Work-Studies are gained on students own merit using their connections from their internships. Hero Offices had previously made offers for Work-Studies, but due to them eventually fighting over more desired students the system was changed. Shota cuts the conversation short and simply states that the first years are still under consideration for participation.
The next day, Izuku's suspension ends and he returns to class and Shota decides to fully explain what Work-Studies are. He introduces Class 1-A to a group of top students known as the Big 3, so they can learn from students with actual experience. Mirio Togata decides to explain through actions rather than words. He then challenges Class 1-A to a fight and promptly defeats all of them (save for Shoto and Katsuki); he then uses it as an example to explain how he used the Work-Studies to improve himself and his Quirk. He explains that students are treated like sidekicks and will do real work for a longer period of time compared to the internships where they were treated like guests.
When Katsuki returns to class Shota announces that many faculty members are against allowing first years to participate in Work-Studies. However, there were also those who argued for it. As a result, only Hero Offices who have employed students in the past will be allowed to employ first-year students.
Izuku reaches out to Gran Torino for a Work-Study opportunity. Gran Torino has to refuse because he's busy working with the Police. He suggests that Izuku ask All Might about working with his former sidekick. Izuku does this, but All Might refuses because he has a broken relationship with Sir Nighteye. All Might asks Mirio Togata to introduce Izuku and he accepts.
Mirio takes Izuku to Sir Nighteye's office and tells him he must make Sir laugh to be accepted. Izuku messes up his first impression but gains Sir Nighteye's interest. Sir decides to challenge Izuku for his employment. He's unimpressed with All Might's decision to pass on One For All to Izuku. He even tells the young student that he's unworthy and that Mirio should've been the one to inherit One For All.
Izuku refuses Sir Nighteye's words and fights on. Sir Nighteye is impressed with Izuku's focus as he fights without ruining the All Might memorabilia posted across the office. Sir Nighteye decides to employ Izuku but reveals that he's only doing it to crush Izuku's confidence. Izuku accepts the challenge and day one of the Work-Study begins immediately. Izuku learns of Sir Nighteye's investigation of the Shie Hassaikai and their leader Overhaul.
Sir Nighteye goes on patrol with Bubble Girl while Izuku joins Mirio. While on patrol, a young girl runs into Izuku. He falls over and looks up to notice Overhaul is the man looking for her. Mirio is able to keep Izuku calm to stop Overhaul from getting suspicious.
Eri refuses to go back with Overhaul, who claims to be her father. Izuku decides to protect the young girl and this irritates Overhaul. The masked villain shows his killer instinct and Eri runs back to his side to protect the heroes from his wrath.
Izuku and Mirio return to Sir Nighteye and inform him about what happened. Sir apologizes for allowing them to run into a dangerous villain. Izuku tells Sir about the young girl but Sir says they can't act until they've waited for the right moment. Overhaul covers his criminal movements well and they must not act hastily against him. Sir orders the duo to return to the office and Izuku's first day comes to an end.
Gunhead and Selkie's Hero Offices refuse to hire Ochaco and Tsuyu because they need to have outstanding accomplishments to be employed. Nejire Hado recruits them both to the Dragoon Hero: Ryukyu's Hero Office. The Dragoon Hero employs them both and is impressed when they take down two giant villains on their first day. She even considers letting them investigate the Shie Hassaikai. 
Suneater tries to help, but his Quirk won't activate. Eijiro manages to corner the mobster and even defeats him in combat. The thug makes Eijiro feel sorry for him and then injects himself with Trigger to enhance his Blade creation Quirk.
The Blade Villain tries to kill Red Riot and puts civilians in danger. Red Riot steps up alone to defeat the villain despite his enhanced Quirk.
Eijiro uses Red Riot: Unbreakable to defeat the mobster and protect the bystanders. The mobster uses tricks Eijiro and tries to escape, but he's stopped by Fat Gum. After all the criminals are arrested, Fat Gum worries about the Quirk Erasing Bullets used on Tamaki. 
Having taken in Fumikage for the Hero Office Internships, Hawks allows Tsukuyomi to work for him again. Fumikage believes he's only there to inform Hawks about the movements of the League of Villains. However, Tsukuyomi is determined to prove himself after being nothing more than a carrier pigeon during the internship.
Tsukuyomi shows off his improvements with his Quirk, using Black Ankh to keep pace with Hawks during patrols. After the first day, Hawks takes Fumikage out flying. They fly to Fukuoka Tower and Hawks tells Fumikage that despite improving, he's still wasting his potential. Hawks advises his pupil to use his wings and fly because there's no reason for Tsukuyomi to be confined to the ground. 
As the Nighteye Office investigation of the Shie Hassaikai picks up traction, Sir Nighteye invites several heroes including the Ryukyu and Fat Gum offices to an information meeting. There they exchange information about the Trigger dealers who Fat Gum's team apprehended. They were a group of middlemen who got their product from the Yakuza organization. The two villains Ryukyu's office fought were involved in using and distributing trigger as well.'
Fat Gum reveals details about the Quirk Erasing Bullets to the group. The one that failed to pierce Eijiro was analyzed by the Police. They found that human DNA was being used. Ryukyu quickly surmises this means the Yakuza are using someone's Quirk to create this drug from their own body. Nighteye informs everyone that Deku and Lemillion encountered Overhaul. Overhaul was with a little girl who's limbs were covered in bandages.
Izuku and Mirio realize that Overhaul is using his Quirk to make bullets out of Eri's body. They are stricken with regret and guilt, and they both swear to take back Eri. Nighteye confirms this will be the focus of an upcoming operation to take down the Eight Precepts of Death.
The Hero Work-Studies are suspended indefinitely following the Shie Hassaikai Incident.
|Shie Hassaikai Arc|
|Chapters||115 • 122 • 123 • 124 • 125 • 126 • 127 • 128 • 129 • 130 • 131 • 132 • 133 • 134 • 135 • 136 • 137 • 138 • 139 • 140 • 141 • 142 • 143 • 144 • 145 • 146 • 147 • 148 • 149 • 150 • 151 • 152 • 153 • 154 • 155 • 156 • 157 • 158 • 159 • 160 • 161 • 162|
|Episodes||62 • 63 • 64 • 65 • 66|
|Battles and Events||Class 1-A vs. Mirio Togata • Overhaul vs. League of Villains |
Hero Work-Studies (Izuku Midoriya vs. Sir Nighteye • Ryukyu Agency vs. Villains • Fat Gum Agency vs. Villains)
Shie Hassaikai Raid (Ryukyu Squad vs. Rikiya Katsukame • Suneater vs. Setsuno, Hojo & Tabe • Red Riot & Fat Gum vs. Rappa & Tengai • Nighteye Squad vs. Toga & Twice • Nighteye Squad vs. Mimic • Lemillion vs. Shin Nemoto & Deidoro Sakaki • Lemillion vs. Overhaul & Chronostasis • Nighteye Squad vs. Overhaul & Chronostasis • Deku vs. Overhaul • League of Villains vs. Snatch)