In Kinnikuman II Sei, the story unfolds years after the original series, focusing on Mantarou Kinniku, the hesitant son of the legendary wrestler King Suguru. Tasked with defending Earth from the menacing dMP group, Mantarou, unlike his brave father, initially shies away from his destiny. Seeking refuge on Earth, he meets Meat, his father's former mentor, who sees potential in him despite his flaws. With Meat's guidance, Mantarou embarks on a transformative journey to fulfill his father's legacy and protect the world from imminent danger.