Two years prior to the current story, Shino received the news of the death of the heroes duo Water Hose, one of whom was her cousin. Water Hose sacrificed themselves to save civilians from the villain Muscular. However, this left their son Kota an orphan, and being Shino his last known relative, is adopted by her.
Shino, along with the the Wild, Wild Pussycats, takes care of Kota, but the deaths of his parents has caused the boy to develop a cold and grumpy personality and a strong hatred towards everything related to heroes. Shino understands her nephew's feelings, but tries to comfort Kota and explain that someday, he will understand why his parents died.
Shota Aizawa brings his students to the Beast's Forest in order to train under the Wild, Wild Pussycats. When the students arrive, Mandalay and Pixie-Bob try to introduce themselves as half of the Pussycat's team, but are interrupted by one of the students: Izuku Midoriya, who recognizes the Pussycats and excitedly explains their history, much to their shock at his knowledge.
Izuku mentions how long they've been active and this irritates Pixie-Bob, who grabs his faces and states that she's eighteen years old at heart. Mandalay explains that Class 1-A is still far away from the base camp and will have to travel there through the Beast's Forest. She tells them they have three hours to fight their way to the forest, and if they don't make it in time, then they won't receive any lunch.
The students try to run back onto their bus, but Pixie-Bob jumps in front of them and uses her Quirk to push them off of the mountaintop and into the forest. Mandalay asks Shota if he's sure the students can handle the training schedule he's laid out for them. Shota replies that the students must work hard to get a full semester's worth of lessons into the summer. They will receive permits to use their Quirks, provisional hero licenses and, most importantly, learn to defend themselves. Mandalay, Shota, and Kota leave Pixie-Bob to test the students.
Almost eight hours later, Class 1-A finally makes their way to the base camp. Battered and bruised, the students are confused on how it took them nearly eight hours to complete a three-hour journey. Mandalay taunts them and says she meant it would take the Pussycat's three hours. Pixie-Bob admits she's still impressed and takes a special liking to Izuku, Shoto, Tenya, and Katsuki for their skills.
Shota asks if PIxie-Bob has always been like thsi and Mandalay states that it's gotten worse and that she's at the age to take a mate. Izuku asks who Kota is and Mandalay replies that he is her cousin. She tells Kota to introduce himself, but he punches Izuku in the crotch and storms off instead.
Mandalay and Pixie-Bob serve the students dinner. Mandalay asks Kota to help her with some vegetables and eventually posts him on top of the wall between the male and female hot springs after Shota tells her tells that one of the boys will try to look at the girls while they're naked. After Kota falls from the aforementioned wall, Izuku brings him to the cabin's office. Mandalay thanks Izuku for saving Kota, and commends his skills for being fast enough to catch him. She explains that Kota simply fainted from the wall and that he will be alright. Izuku questions Kota's views on heroes, unable to understand why he hates them so much.
Pixie-Bob enters the room and tells Izuku that Kota's parents sacrificed themselves protecting citizens. Mandalay explains that Kota sees their sacrifice as them abandoning him for their hero work. She admits that Kota doesn't like the Pussycats either because they're pro heroes and that he may feel like he's only around them because he has nowhere else to go.
The next day, the full Wild, Wild Pussycats team unites to train both Class 1-A and Class 1-B. Mandalay and her teammates all explain their Quirks and how it will help train all forty students at once. Mandalay says her Quirk is Telepathy, allowing her to give advice to every student throughout the camp.
The evening of the following day, Class 1-A, and Class 1-B participate in a test a courage in the forest. During which, Mandalay and the Pussycats notice the mountainside start to burn. Suddenly, Pixie-Bob is attacked by two members of the League of Villains.
Mandalay uses her telepathy to instruct everyone to avoid the villains and return to base camp. She tells the students close to her to return as well and prepares to fight Spinner and Magne with Tiger. In the ensuing battle, Mandalay manages to avoid Spinner's giant sword and tries to strike back after distracting him with her Quirk. She misses and then Magne uses her Quirk to magnetize Mandalay towards her. Tiger saves her from Magne's attack. Once she's free, Mandalay informs Tiger that she cannot contact Ragdoll.
Mandalay continues to fight in close quarters with Spinner. She's forced to evade several quick attacks from his giant blade until Izuku returns and breaks it with a powerful dropkick. He informs her that he was able to secure Kota's safety and that he has a message from Shota. Mandalay uses her Quirk to relay Shota's message to all of the students in Class 1-A and 1-B. Shota grants them permission to fight back against the villains in order to protect themselves.
Mandalay tells Izuku to return to base camp, but he refuses, replying that he still has something to do. He rushes off, but not before telling Mandalay that one of the villains targets is a student named "Kacchan." Spinner stops Magne from attacking Izuku and they argue over Stain's principles. Mandalay knocks Spinner down with a punch while he's distracted. Mandalay relays Izuku's warning to the students and asks that Kacchan should try to avoid combat and stay in a group.
The villain Vanguard Action Squad escapes the forest after achieving their goal of kidnapping Katsuki, but Mandalay and Tiger discover that their partner Ragdoll has also been kidnapped. Because she has to take care of her nephew Kota, Mandalay cannot participate in the rescue operation with her partner Tiger.
The rescue operation ends successfully. Katsuki is rescued and All For One, the leader of the Villains League, is arrested and sent to prison. Ragdoll is also rescued, but she can no longer be a hero because All For One had stolen her Quirk. Mandalay and her companions try to comfort a disconsolate Ragdoll.
When the Pussycats visited U.A. High School, Shino and her team do their introductions again before giving the Class 1-A students chocolates she made. Shino watches Kota and Izuku talk before she points out to the new shoes Kota has, which look exactly like Izuku's shoes. This leaves Kota embarrassed after Izuku point out the match and Shino giggles at the sight.
As he gives out tea, Rikido asks why the Pussycats have decided to pay them a visit. They reply that they came to celebrate Ragdoll's reinstatement to provide support for the Pussycats, at least as a secretary, due the loss of her Quirk. They are informed that All For One cannot transfer the Quirk he stole back to its original user or to another person
Momo wonders why the Pussycats would rejoin at this time; Mandalay states that the JP Hero Billboard Chart will be broadcasted and that they are 411th on the billboard chart. Eijiro assumes that the Pussycats have returned so that they can rank higher, to which Ragdoll refutes and replies that they have returned due to their high approval ratings meaning that there are many fans who want to see them back in action.