Selkie/Synopsis

Vs. Hero Killer Arc
Selkie accepts Tsuyu Asui's request to do her Hero Agency Internships with him at the Oki Mariner. From the first day he put her to train with the rest of the crew or to maintain and clean the ship. One day, he finds Tsuyu and his sidekick Sirius sitting down and scolds them for slacking off. Sirius corrects him, stating they had already finished their tasks. Selkie apologizes for jumping to conclusions, using his cute persona, much to Sirius dismay, who reminds him that he cannot be adorable because he's too rugged for that, which puts Selkie off.

One of his crewmembers says they've received a mission from the guard coast. Selkie immediately gives his crew the order to set sail, and during the journey he explains they are requested to patrol a certain area in search of stowaways, as they have been on a trade ship called Nysan to which part of its cargo disappeared was missing. He asks Tsuyu about what she thinks about it. She replies that the stowaways were probably smuggling brokers who moved the cargo to another ship and fled before the arrival of the guard coast. Surprised, Selkie tells her that she is right.

Selkie takes to the water himself to search for the ship using his Spotted Seal Quirk capabilities while the rest of the crew search via radar. They search for hours and it gets dark, but they can't find anything. Then they are informed that a fishing boat thought to belong to the stowaways is in their area after escaping another pursuer. Selkie returns to the ship after confirming the location of the boat and they eventually happen upon it.

Selkie and a couple of his crewmates board the fishing boat. Tsuyu wants to participate but Selkie denies the request and orders her to stay on the ship, much to her dismay. Selkie and his men interrogate the alleged fishermen, but are fooled and locked in one of the ship's holds. The stowaways run away, but Selkie uses his echolocation ability to inform Selkie that this boat was a decoy and they must pursue the real stowaways.

As Sirius, Tsuyu, and Mick follow his orders, he manages to escape the fishing boat. He contacts Sirius's group without knowing that they are at the time facing the criminal ringleader Innsmouth, but Tsuyu relays an S.O.S across using Sirius's radio. Selkie swiftly swims to their aid, and along the way defeats the villain's lackeys. He finds Tsuyu and Sirius overpowered by Innsmouth himself. Innsmouth blinds Selkie using his ink, but he uses echolocation to find and defeat him. Afterward, the stolen goods are returned and Selkie claims that Tsuyu will make a great hero one day.

Shie Hassaikai Arc
When Class 1-A is told that only Hero Offices with proven track records histories are allowed to accept interns, Tsuyu considers calling Selkie. Unfortunately, Selkie's agency doesn't meet the proper U.A. standards, and Tsuyu interns under Ryukyu instead.

Endeavor Agency Arc
Out in the Pacific Ocean, the Oki Mariner is pursuing a smuggling ship, with Selkie threateningly ordering the crew to stop. Sirius advises her captain not to provoke them, so he decide to act kind and cute, much to Sirius's disgust. One of the smugglers jumps out in front of the ship, and generates a large amount of smoke with his Quirk after injecting a drug. Selkie orders his crew to continue the chase, showing concern that the drug is Trigger. Sirius tells him that the stateless ship departed from Kaflin, and Selkie connect him it a recent incident in that country, where an illicit Trigger factory was destroyed but all the product had disappeared.

The Oki Mariner comes out of the s massive smokescreen but the ship suspected of smuggling Trigger managed to got away. Sirius deduces the ship is hiding somewhere in the Verize Islands. Due to the enemy crew having access to Trigger and the islands being difficult to navigate, Selkie sends a request for Team-Up to the Ryukyu Agency.

Hours later, the Oki Marine crew meets Ryukyu on one of the islands. She brought along her sidekicks Nejire, Ochaco, and Tsuyu. Selkie is happy to see his former trainee and to see how much she has improved since then, while Tsuyu is very grateful for what she learned during her internship in the Oki Mariner. He then tells the girls to have fun on the beach before heading out to find the ship.

Ryukyu asks Selkie why they didn't go straight to work. Selkie replies the smuggling ship wouldn't make a move until it's dark, so he wants to let the girls relax and have a little fun. Ryukyu understands he wants to boost the girls' morale from the constant stress brought on by hero work, by letting them to enjoy the moments of peace and thus have a stronger desire to protect it. Ryukyu understands he wants to boost the girls' morale from the constant stress brought on by hero work. By letting them to enjoy the moments of peace, they will develop a stronger desire to protect it.

At dusk the two teams search for the villains. Once out to sea, Selkie heads into the water to search for the boat, with Froppy on his back, while Sirius remains in contact with Ryukyu. Selkie and Froppy track the smuggling ship down still under water, whose location he delivers to Sirius using his echo location in morse code. The other heroes surround the smugglers, who once again use a smokescreen in order to escape, but the heroes were counting on it.

Using the smoke itself, Selkie boards the ship and defeats two of the criminals, but the drugs have already been transported onto a seaplane, which began to take off. Selkie is worried they'll lose them, but Sirius reminds him not to give up too soon. She helps Ochaco to board the airplane, and once inside she takes down the smuggler who pilots it. Ryukyu safely lands the plane on the water. They find Trigger in the ship and are glad that they stopped the smugglers in time.

Later, when the girls are relaxing once more, Selkie and Ryukyu discuss their findings, including that the smugglers were couriers for an anonymous employer and that the drugs were headed for Otheon in Europe, though Selkie declares that there's nothing to worry about as they stopped their plans.

Paranormal Liberation War Arc
By the end of March, thanks to Hawks' espionage and police investigation, the Hero Public Safety Commission discover several hideouts of the Paranormal Liberation Front - the most important being Jaku General Hospital and Gunga Mountain Villa - and organize a large force of heroes to raid both and take down the villain organization. Selkie is part of the team of heroes in charge of raiding the Gunga Mountain Villa.

Attacking by surprise, the heroes nearly overwhelmed the PLF, but the situation drastically changes when Gigantomachia springs into action to reunite with Tomura Shigaraki at the hospital, leaving a trail of destruction in his wake. While several heroes try to stop the hulking beast, the rest face the PLF soldiers. Selkie prepares to help fight Re-Destro.