Movie
Description
Seiuchin is a walrus-themed Chojin portrayed as a devoted friend and self-proclaimed brother to Mantaro Kinniku, exhibiting a consistently gentle, kind-hearted, and easy-going nature. He routinely prioritizes allies' needs through domestic support and combat assistance, though his benevolence occasionally manifests as perceived vulnerability in battles. His physical form mirrors a walrus with prominent tusks, severe overweight, and black beady eyes, complemented by black thigh-length boots and a signature long white forehead ribbon; walrus attributes may constitute a suit revealing pale skin beneath torso strings.

His Irish family includes mother Suzie and younger sister Dorothy (both sharing his resemblance), with father Robert perishing in a childhood fishing accident. Suzie trained him in swimming, and his family regularly attends his matches. As a Hercules Factory student, he ranked second in his first-year cohort, mastering martial arts theory and techniques despite an unassuming presence. Graduating alongside Mantaro, Terry the Kid, and Gazelleman, he received assignment to defend Hokkaido for its environmental compatibility.

Key narrative developments include:
- Abandoning his post during the d.M.p conflict to aid Mantaro in Tokyo. Forced into combat against MAXman mid-meal, he initially overwhelmed his opponent with brutal tactics but succumbed to trickery after granting respite. Enduring critical injuries to let Mantaro analyze MAXman’s techniques, his blood splattered spectators before gifting his bandana to Mantaro as a keepsake.
- Facing Clioneman in the Hercules Factory First Year Replacement Matches atop a stone platform. After familial encouragement helped him break free from absorption into Clioneman’s watery form, he lost when impaled during the escape.
- Later captured while transporting Fork the Giant, he was held hostage until Mantaro intervened.
- As Ireland’s champion in the revived Chojin Olympics after defeating Sharkman, he suffered disqualification when daruma dolls collapsed onto him, urging Mantaro to claim victory.

A drastic transformation unfolded in the Ultimate Chojin Tag Tournament arc. Following persistent dismissive remarks from Mantaro about his prowess, he allied with Neptuneman, enduring days of bat-infested cave torture that awakened feral instincts. Reduced to a near-mute, bloodthirsty beast under a control helmet and leash, he tore faces from opponents like Ilioukhine and Barrierfreeman alongside Neptuneman. Against Jade and Scarface, Scarface’s sacrificial face-ripping began reversing his savagery. Confronting Warsman and Mammothman fully restored his original persona, provoking Neptuneman and Mammothman to rip off his face. After surgical reattachment, he rejoined the Justice Chojin and apologized to comrades.

Across media, his combat traits encompass immense strength, speed, and durability inherent to Chojin physiology, augmented by abilities to expand to building-sized proportions and achieve unaided flight. Frequent depictions show him carrying or consuming fish for temporary capability enhancements.