Gleipnir is a dark supernatural action manga set in a brutal survival game where mysterious coins grant monstrous powers, following Shuichi Kagaya, a timid high school boy who can transform into a giant mascot-like creature, whose life spirals into violence when he partners with the ruthless and driven Claire Aoki, crawling inside his transformed body to fight enemies as they hunt for answers behind the deadly system controlling their world, delivering graphic combat, psychological tension, and shocking twists as alliances fracture and hidden motives surface. As the story escalates, it explores themes of identity, moral corruption, dependency, trauma, and the loss of innocence, blending visceral horror with uncomfortable emotional dynamics that constantly challenge the line between victim and monster. Combining action, horror, psychological thriller, and ecchi elements, the series gained notoriety for its disturbing tone and unpredictability, later receiving an anime adaptation that expanded its audience and debate around its provocative themes, also known as Gleipnir manga, グレイプニル, Gureipunitu, Gleipnir anime, Shuichi Kagaya manga, Claire Aoki, dark survival battle manga, psychological horror action series, and transformation power manga.