As summer arrives for the students at UA Academy, each of these superheroes-in-training puts in their best efforts to become renowned heroes. They head off to a forest training camp run by UA's pro heroes, where the students face one another in battle and go through dangerous tests, improving their abilities and pushing past their limits. However, their school trip is suddenly turned upside down when the League of Villains arrives, invading the camp with a mission to capture one of the students. Boku no Hero Academia 3rd Season follows Izuku "Deku" Midoriya, an ambitious student training to achieve his dream of becoming a hero similar to his role model—All Might. Being one of the students caught up amidst the chaos of the villain attack, Deku must take a stand with his classmates and fight for their survival. [Written by MAL Rewrite]

In spite of his best time-leaping efforts, Takemichi Hanagaki continuously fails to prevent the present-day death of Hinata Tachibana, his adolescent love. The adult Takemichi grapples with grief and the ramifications of the Tokyo Manji gang's criminal empire—an unintended product of his timeline meddling. Though the gang once operated under the idealistic Manjirou "Mikey" Sano, it has now been taken over by the malicious Tetta Kisaki and, as a result, has abandoned its original optimistic intent. Despite feeling hopeless, Takemichi travels to the past once again to investigate Black Dragon, a rival motorcycle gang whose actions ultimately lead to Hinata's demise. There, he meets the young Hakkai Shiba, a fellow gang member whose older brother, Taiju, tyrannically rules Black Dragon. When Taiju brutally beats Takemichi in a one-sided street brawl, Hakkai attempts to withdraw from Tokyo Manji in apology—an act that Takemichi must prevent to spare Hakkai a grim future. Through a shared tragedy, Takemichi bonds with Chifuyu Matsuno, establishing a close comradery both boys desperately need. With Chifuyu on his side, Takemichi works to unravel the fates of Black Dragon's members, fighting to create a happy future for his loved ones.

Wataru Sajou is infamous in his school for persistently seeking the attention of his crush, Aika Natsukawa. His usual day revolves around shadowing her and confessing his undying love at every turn. However, a moment of epiphany leads Wataru to relinquish his childish behavior and face the reality that she will never return his one-sided feelings. He distances himself from Aika and spends his newfound spare time with his friends and in the company of other lovely girls. As Wataru moves on, Aika starts approaching him in unusually suggestive ways—making him question whether giving up on his love was the right decision after all.

On Christmas Eve, four-year-old Miri Unasaka arrives in Tokyo completely alone, in search of her father. The bright lights and merry atmosphere guide Miri to a big hotel and a man with a delicious-looking cake. However, the child has just unknowingly walked into the center of an elaborate, foolproof plan for assassinating a dangerous mafia boss. Professional assassins Kazuki Kurusu and Rei Suwa live together, fleeing memories of their grim childhoods and avoiding emotional connections. When their mission goes awry and they end up bringing Miri home, there is only one reasonable thing to do: return Miri to her mother. But the girl's innocent laugh and pure worldview quickly enamor her to Kazuki, who secretly enjoys playing a parent, and it is not long before Rei's impenetrable heart makes room for Miri. Miri's every move is unpredictable, and Kazuki and Rei find raising an energetic child harder than any of their missions. Although it presents a great risk to their careers, Kazuki and Rei—both assuming the affectionate nickname "papa"—decide to provide Miri with a normal childhood despite all the odds stacked against them.