Yo Shindo/Synopsis

History
At some point, Yo got enrolled at Ketsubutsu Academy High School.

Provisional Hero License Exam Arc
On the day of the Provisional Hero License Exam, Ms. Joke introduces Class 2-2 to Shota Aizawa's Class 1-A from U.A. High School. Yo greets Izuku Midoriya, Denki Kaminari, and Kyoka Jiro by shaking their hands and commenting on their struggles throughout the school year. He claims they have strong hearts and tries to shake Katsuki Bakugo's hand because he had an especially hard time as of late. Katsuki refuses Yo's hand and sees through his facade. Eijiro Kirishima apologizes for his behavior but Yo says that it's just a sign of his strong heart.

The Ketsubutsu second-year students change into their hero costumes and wait inside the crowded stadium for orientation. Following Yokumiru Mera explaining the rules, the arena is revealed and the Ketsubutsu students move together in preparation for the start of the first phase. Immediately after the test starts, Yo leads an ambush for the "crushing of U.A.". Yo tells Izuku that he knows his power hurts his body and the entire class throws their projectiles at Class 1-A. Class 1-A easily deflects all the balls and Yo looks impressed by their defenses.

Yo tells Shikkui that he expected U.A. students to handle an attack of that caliber. Shikkui and Itejiro attack using their Quirks, but the U.A. students deflect them with their Ultimate Moves. This makes Yo realize that Class 1-A has grown considerably stronger since the U.A. Sports Festival. Seeing that Class 1-A's defenses are too strong, Yo tells his classmates to get back so he can break through himself. He ramps his Vibrate Quirk up to "Maximum Force" and uses his Tremoring Earth Ultimate Move to create an earthquake that destroys the battlefield.

Sixty people are announced to have passed the first phase. Yo hides with his classmates and he updates them on the situation. The U.A. students have been split up and other students have come to the battlefield trying to take advantage. This has created a chaotic situation where students are rushing to try and pass before time runs out. Yo puts on his true face and advises his class to take advantage of those who are using up their stamina and stricken with tunnel vision looking for U.A. students. Yo and his class find new victims and eliminate them to pass the first phase.

During the final phase of the exam, Yo helps lead rescue operations. He sets up the first aid area with his classmates and rescues citizens from H.U.C. during the early portion. When Gang Orca and his sidekicks attack acting like villains, Yo rushes to the front lines. He tries to keep the "villains" away from the rescue station by creating tremors with one-second intervals between them. However, Gang Orca hits him point-blank with supersonic waves and appears to paralyze him.

Shoto Todoroki and Inasa Yoarashi compete to defeat Gang Orca and end up putting Yo in danger by recklessly blowing around fire. Izuku carries Yo away from the fire and to safety. Gang Orca's Sidekicks rush to destroy the station after Inasa and Shoto are immobilized. Yo suddenly recovers and creates tremors to keep the villains back. Izuku is surprised Yo can move. He explains that his Quirk vibrates his brain all the time so he's resistant to sonic attacks. Yo says he was planning to surprise Gang Orca with the aforementioned tolerance, but the first years got in his way. Yo gets angry and Izuku is surprised by his sudden shift in tone. Yo works with Izuku on keeping the "villains" back and getting everyone to safety.

Following the end of the licensing exam, Yo changes into his school uniform and finds his name on the list of participants who passed.

Endeavor Agency Arc
When the Hero Public Safety Commission required that all Hero Course students participate in Hero Work-Studies, Yo teams up with his classmates, Tatami, Shikkui and Itejiro.

Tartarus Escapees Arc
In an abandoned city, Yo and Tatami, now in their third years, are searching for a group of civilians to send to the evacuation zones. Yo is confident that he can convince them, bringing up the Nomu and the recently escaped "Jailbreaker", but the distrusting civilians reject their offer to lodge at Ketsubutsu High. Disappointed, the two students leave, and Yo angrily states that he could have brought the building down and dragged them out if he was allowed to.

Suddenly, Tatami receives an alert from Shikkui, who is warning them that Jailbreaker is approaching their location. Suddenly, Muscular, who now goes by Jailbreaker, crashes onto a nearby building, ready to shed more blood. Yo asks Tatami to evacuate the citizens while he goes to fight Muscular. Muscular easily pins down Yo with his muscle fibers, and slowly begins to crush him to death. Yo attempts to stun the murderer using Tremoring Earth, but he produces more fibers and is seemingly unfazed by the attack. As Tatami and the civilians watch in horror as Yo is about to be killed, Muscular is flung away and the unconscious Yo is rescued by a masked figure who is none other than Izuku Midoriya.

Deku avoids Muscular using his new Smokescreen Quirk, and hands Yo over to Tatami, who scolds him for being reckless. Yo's efforts were not in vain, however, as his vibrations dealt damage to Muscular's tendons, allowing Deku to swiftly defeat him. The civilians bring out a stretcher for Yo, and decide to hear out the students because they don't want anyone else getting killed. Yo regains consciousness and thinks about how the masked figure looked similar to a kid he met at Provisional Hero License Exam, but feels a different vibe from him, wondering if they really are the same person.