Inuyashiki follows a lonely, elderly man named Ichiro Inuyashiki who is terminally ill and neglected by his family. After being killed in a freak explosion at a park, he is rebuilt as a powerful cyborg weapon. Struggling with his new form, he decides to use his abilities to help people and become a hero, finding a renewed sense of purpose. However, a young, sociopathic high school student named Hiro Shishigami was also killed and rebuilt in the same incident. Unlike Inuyashiki, Hiro uses his devastating powers for violence and murder, relishing the chaos. The story becomes a brutal, high-stakes conflict between Inuyashiki's desperate quest to do good and Hiro's nihilistic rampage. Readers enjoy the series for its unique premise, the stark contrast between its unlikely hero and terrifying villain, and its exploration of themes like aging, loneliness, mortality, and what it means to be human. The fast-paced, violent action and emotional depth keep audiences gripped.