Selkie is a man with a muscular physique, but with the appearance of a humanoid spotted seal that has a gray beard.
He sports a full body wetsuit as his hero costume, featuring yellow goggles, retractable flippers and a stylized "S" featured on the left shoulder.
Selkie is a confident, kind, and professional individual who prioritizes his hero work and protecting his crew. He has a tendency to try (and succeed in) making himself look cute, despite his macho appearance, much to the annoyance of his sidekicks. Even so, he can be quite stern when the situation calls for it.
Aboard the Oki Mariner, Selkie yells at Sirius and Tsuyu Asui for slacking off but apologizes using his cute persona after he finds out they have finished all their work. He and the crew later sail off to pursue stowaways who stole cargo from a trade boat. When they happen upon the supposed criminal ship, Selkie goes without Sirius and Tsuyu to investigate.
He and two of his sidekicks investigate the ship, only to be trapped inside by Innsmouth's lackeys. Selkie only returns to the action when Tsuyu relays an S.O.S across using Sirius's radio. Selkie finds Tsuyu and Sirius overpowered by Innsmouth himself. Innsmouth blinds Selkie using his ink, but Selkie 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.
When Class 1-A was told that only Hero Offices with good histories were allowed to accept interns, Tsuyu considered calling Selkie. Unfortunately, Selkie's agency did not meet the proper standards, and Tsuyu interned under Ryukyu instead.
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, being the most importants the Jaku General Hospital and the 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 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. Selkei prepares to help fight Re-Destro.
Spotted Seal (ゴマフアザラシ Gomafuazarashi?): Selkie's Quirk grants him the attributes and abilities of a spotted seal. He can hold his breath for long periods of time and utilize echolocation when traversing dark waters or when his sight is hindered during combat. He also has above human strength.
- Skilled Swimmer: Having the attributes of a spotted seal, Selkie is an excellent swimmer.
Retractable Flippers: A pair of shoes with water flippers that flip back behind his legs when he is not in the water.