When under the effects of Trigger, Leviathan is a hulking man with bleach white skin, black markings on his face and forearms, and a single row of brown spikes running down his spine. He has a relatively small head, with beady orange-yellow eyes and a wide set of teeth. On Leviathan's fingers and toes are spiraling red appendages. There is also a set of "tubes" with the same appearance stemming from is back and connecting to his head. He wears torn black plants with a brown belt.
Leviathan has only been shown briefly while not on Trigger. He is still very muscular, though not to the extent of his enhanced form. He had fair skin and the spirals on his head were smaller.
Like most Humarise members, Leviathan is devoted to carrying out Flect Turn's plan, although not much is known about his personal beliefs or personality as he is often using Trigger, which sends his mind into a violent rampage.
Overall Abilities: Leviathan was recognized as an incredibly powerful force, further exemplified by his moniker, the "Rampage Villain". He possessed a great handle on his powerful Quirk, Helical Scythe, which he used to overwhelm his opponents while under the effects of Trigger. He was capable of overwhelming and almost defeating Shoto Todoroki, one of U.A. High School's most powerful students with his overwhelming physical might and immunity to the latter's abilities.
Immense Strength: Befitting his incredibly muscular build and size, Leviathan possessed enormous levels of physical strength, showcased in his battle against Shoto. He could destroy a massive amount of ice with his tendrils and shatter solid concrete. He could instantly shatter a large portion of the Humarise Hideout's floor and carry large chunks of ice with ease.
Immense Durability: Leviathan possessed incredible levels of durability and endurance. He could easily bathe in Shoto's fire and withstand several of his high-powered blasts, as well as endure several tons of rubble and ice falling on him along with a large drop into a sewer canal.
Helical Scythe (ヘリカルサイズ Herikarusaizu?): Leviathan's Quirk allows him to control powerful, twisted red appendages on his fingers and head. These tendrils can pierce through things like a drill and have a wide range of attack. He can use the tendrils to manipulate the elements around him, like the flow of water to ensnare opponents and drown them, or fire to create a giant construct of himself to swallow his opponents alive, as well as use them as a whip for a ranged attack.
Trigger (トリガー Torigā?): Leviathan uses Trigger before he encounters his opponent and rushes them with his overwhelming power.
- Leviathan's black and white color scheme, coupled with his muscular frame, "tubes" snaking on his body, and having a constant reliance on a performance-enhancing drug, makes him resemble the DC villain Bane. His white skin color and wide smile also make him resemble The Joker. So a possible inspiration for the character could be when the Joker got powered up by Venom (the drug that is used by Bane) in the videogame Batman: Arkham Asylum.
- Leviathan also uses the drug Trigger. Similar to how Bane uses Bane Venom.
- Leviathan's Japanase voice actor, Shogo Sakata, also voices Enma Kannagi.
- Leviathan's English voice actor, Marcus D. Stimac, also voices Yawara Chatora.
- Leviathan is referred to as the Rampage Villain (暴走ヴィラン Bōsō viran?).
- My Hero Academia Manga: Volume World Heroes.