Anan Kurose/Synopsis

Vigilantes Beginnings Arc
One day, the villain Kuin Hachisuka uses her Queen Bee Quirk to inject Trigger into innocent civilians, causing an Instant Villains outbreak. Detective Naomasa Tsukauchi immediately call for backup. Thirteen and other heroes appear immediately and quickly suppress the outbreak.

Sometime later, Thirteen is called into a meeting at the police station with several of the heroes who also had participated in suppressing the outbreak like Eraser Head, Endeavor, Midnight, Ingenium and more. Once in the meeting room, detective Eizo Tanuma informs them that the Instant Villains they had defeated are unwilling civilians who were injected with Trigger by someone. The officer explains that the people in question were more victims than they were villains.

Thirteen states that she would assess the situation at the scene more carefully- as heroes, they must not bring harm to innocent citizens. This is in direct opposition to Endeavor's answer, greatly angering him as a result. Once the meeting is over, she returns to her duties.

U.S.J. Arc
When Class 1-A is brought to the Unforeseen Simulation Joint, Thirteen explains that they will train there to make use of the facility's simulations of all kinds of disasters and accidents. Class 1-A's homeroom teacher, Shota, asks Thirteen where All Might is, and Thirteen replies that he was doing too much hero work to make it on time. Before rescue training begins, Thirteen speaks to the students about the dangers of Quirks and why they need to be regulated, as well as how the students will now be training to use their Quirks to save people. Thirteen concludes her speech by saying they hope everyone will understand how to wield their Quirks in rescue situations by the end of the exercise.

However, before the training exercise begins, villains appear through a Warp Gate. Shota tells Thirteen to protect the students and leaps into action. While trying to lead the evacuation for the students, Thirteen is confronted by Kurogiri, who asks where All Might is.

As Kurogiri talks, Thirteen attempts to use her Quirk without being noticed but is unable to when two of the students attack Kurogiri. Katsuki Bakugo and Eijiro Kirishima seem to land an attack, but Kurogiri remains unfazed. Thirteen pleads for the tandem to move out of the way, but Kurogiri capitalizes and uses his Quirk to separate the class by teleporting the students to several different places within the facility. Thirteen remains at the entrance plaza, along with Tenya Ida, Ochaco Uraraka, Hanta Sero, Rikido Sato, Mina Ashido, and Mezo Shoji.

Thirteen commands Tenya to use his Quirk to run to the school and alert the faculty of the attack because one of the villains is jamming his communications. Kurogiri overhears his plan and prepares to stop them, but Thirteen uses her Quirk to suck his mist body into a Black Hole.

Kurogiri commends Thirteen on her powerful Quirk, but also comments that they have little fighting prowess before he opens a warp-gate behind Thirteen, causing Thirteen's Quirk to backfire onto her. Half of Thirteen's suit is disintegrated by Black Hole and they are incapacitated.

Eventually, All Might arrives, as well as the U.A. High School faculty members called by Tenya. The group manages to repel most of the villains, forcing Kurogiri and Tomura Shigaraki to try and escape. Thirteen is helped to her feet and tries to stop the villains from using Kurogiri's Quirk, but they teleport away. Afterwards, Thirteen is brought to Recovery Girl to be healed. Detective Naomasa confirms that she has recovered from her injuries when he informs the students of her condition.

U.A. Sports Festival Arc
During the U.A. Sports Festival, Thirteen spectates the events from the faculty section of the stands. As the battle between Izuku Midoriya and Shoto Todoroki begins, Thirteen asks All Might if Izuku and Shoto are the ones that jumped in to save them at U.S.J, which All Might confirms.

Final Exams Arc
Prior to Final Exams at the end of the first years' first term, Thirteen meets with her fellow faculty members. The faculty discuss changing the finals format from facing robotic villains to fighting against the teachers. Thirteen comments that this may be too difficult for the students, but they all ultimately agree on the change. Thirteen joins the teachers at the Final Exams practical portion test site to meet Class 1-A. Thirteen is placed against Ochaco and Yuga Aoyama.

In their battle, Ochaco and Yuga reach the escape gate but before they can go through it, Thirteen stops them with Black Hole. The duo holds onto a guardrail to avoid being sucked in, thus being unable to go forward or backwards, trapped in place while Thirteen advances on them.

Yuga fires his Navel Laser from his knees (thanks to his hero costume) at Thirteen, but the attempt fails as Thirteen easily sucks in the laser. Ochaco, surprised by a comment by Yuga, accidentally lets go of the guardrail, and Thirteen stops using her Quirk to protect Ochaco from being turned to dust.

Ochaco uses the unexpected momentum to turn the situation to her advantage and faces Thirteen directly. Using the combat skills she learned from interning with Gunhead she manages to pin down the Pro Hero with Yuga's assistance and handcuffs Thirteen.

Provisional Hero License Exam Arc
Thirteen goes to Ground Beta to attend principal Nezu's speech to all the students of the U.A. about the current situation after All Might's retirement and how it will affect classes and their lifestyle.

Shie Hassaikai Arc
Thirteen overhears the conversation between Izuku and Toshinori at the U.A. Administration Office. She agrees with Toshinori that's too early for first years students to conduct Hero Work-Studies. During the duration of the program, she is dedicated to supervising the students' training.

Pro Hero Arc
At U.A., Thirteen, along with other teachers, watches a report of the fight between Endeavor and the High-End Nomu Hood. When Endeavor is injured and overwhelmed by the Nomu, Shota asks Eri to go to her room, so she can not see the violent scene, and leaves the girl in Thirteen's care while he heads towards Shoto's location, concerned about how this can affect him.

Paranormal Liberation War Arc
By the end of march, Many Heroes across Japan are rallied by the Hero Public Safety Commission to take down the recently formed Paranormal Liberation Front with the merge of the League of Villains and the Meta Liberation Army. They have info about the main hideouts of the villain organization thanks to Hawks. Thirteen is assigned to the Jaku General Hospital raid team along with several other Pro Heroes and lead by Endeavor.

At Endeavor order, the raid begins. While one group is in charge of evacuating patients, visitors, and hospital staff from the building, another group is in charge of arresting Garaki, although the situation gets complicated when he releases a horde of Nomu to escape to his secret laboratory to awakes Tomura from his stasis.

In spite of everything, the heroes defeat the creatures and beging to storm into the laboratory, preventing Dr. Garaki from awakening a Tomura Shigaraki. Facing his defeat, a heartbroken Dr. Garaki declares that the Devil's Dream has finally ended. However, against all odds, Tomura Shigaraki awakens, despite having previously verified that his heart was not beating. He immediately uses his decay, which spreads rapidly through the laboratory, disintegrating everything in its path.

The heroes try to escape from the lab as it's being torn to shreds. Thirteen apparently tries to use her Quirk to stop the destruction instead of running away, but she does not succeed and the entire hospital ends up completely disintegrated, along with dozens of heroes. Only a few manages to escape.

Miraculously, Thirteen somehow manages to survive the Decay, though not without consequences as she had lost her left arm. Despite her injuries, Thirteen and other surviving heroes try to prevent Tomura/All For One from escaping with a handful of allies and Nomus, but they are not successful.