Chapter 45: Aquarium

Class 1-A turns up at Takoba Aquarium on Mirio Togata's invitation, arranged because Eri wanted to see one, and finds the tanks empty. Guests are storming out. A staff member explains to Izuku Midoriya that the enclosures connect straight to the ocean, so the animals appear to have simply swum off on their own.

Koji Koda volunteers Anivoice, and Mirio points out that an offshore search needs mobility and detection. Shoto Todoroki can freeze footing across open water, Kyoka Jiro signs on to listen for movement, and the three set out. Eri asks Mirio if this counts as a mission and whether police involvement follows; he reassures her there is nothing to worry about and steers her toward the remaining fish. With nothing left to display, Minoru Mineta asks for a plan and the rest of the class settles on impersonating sea life. Offshore, Shoto notes the immobile creatures never left, and Kyoka suggests questioning them, but Koji's Quirk will not connect. She wonders whether something is cancelling it the way Eraser Head does, though Shoto's ice works fine, which he treats as useful information in itself.

Kyoka picks up a school of fish and they run out across Shoto's ice, where Koji finds one injured. He insists on treating it rather than leaving it, explaining that his Quirk runs on mutual trust, but the creature is too weak for him to reach. The water then churns and a squid-like man surfaces amid a mass of animals. He gives his name as the Master of the Waves, recalls the wounded fish to his side and declares that since society on land will not obey him, he will command every living thing in the sea instead, and attacks the three.

Back at the aquarium, Mirio judges that the costumed act has run out of road. Koji's Quirk fails against the villain's control, and a blow sends him under while sea creatures swarm Kyoka and Shoto. Eri meanwhile drifts toward the dolphin exhibit, and Izuku, Minoru, Eijiro Kirishima, and Mirio scramble after her before she can learn the truth. Swarmed underwater, Koji refuses to hurt the animals to save himself. He reaches out instead and a whale answers, crashing onto the Master of the Waves and shattering his hold. Kyoka observes that the whale acted on instinct despite being under the villain's Quirk, and she tells him his heart is a kind one. Home afterward, Mirio checks on a sleeping Eri and catches her thinking about a drawing of that whale and about going again with him, which suggests she had been humoring them all along.

The Master of the Waves debuts, using his Quirk to empty the aquarium and command sea life.

Koji Koda's Anivoice is shown to depend on mutual trust rather than force, and it fails while the villain holds the animals.

Koji summons a whale that acts on instinct, breaking the villain's control and ending the fight.

Written and drawn by Yoco Akiyama, this lands as chapter forty-five of My Hero Academia: Team-Up Missions. It runs 26 pages, released May 2, 2024 in the June 2024 issue of Saikyo Jump, and collects into Volume 7. Deku and Anima share the cover.