Gleipnir is a Japanese manga series written and illustrated by Sun Takeda. It follows the story of Shuichi Kagaya, a high school student who can transform into a monstrous creature with superhuman abilities. After discovering a girl named Claire Aoki who knows his secret, they become entangled in a dangerous game involving other monster-like beings. The series explores themes of identity, power, and the consequences of one's choices. As Shuichi and Claire navigate their complex relationship, they face various challenges and adversaries, leading to intense action and psychological drama throughout the narrative.