The film revolves around three boxers from different backgrounds. Akira Munehayashi (played by Mirai Moriyama) has fallen from his peak as a professional boxer to become a marginal underdog, always treated as a 'soft touch' to boost others' confidence. He loses himself and even considers giving up boxing but after hitting rock bottom, he awakens and ultimately returns to the ring to search for the meaning of life. Ryuta Omura (played by Takumi Kitamura) is a young boxer carrying a secret; abandoned by his parents as a child, he has walked down a rebellious path and his shattered life is revitalized through boxing, bursting onto the scene with unstoppable momentum. Shun Miyamaki (played by Ryo Katsuragi) is a second-generation 'star' comedian. Under his father's doubts, he loses his sense of self and cannot find his footing. He participates in a boxing match as part of a TV program's concept, attempting to genuinely prove himself and win through boxing behind his humorous façade. 'Underdog: Survival' primarily focuses on the ultimate showdown between Akira Munehayashi and Ryuta Omura. After his match against Shun Miyamaki, Akira faces the choice of retirement once again, while the determined newcomer Ryuta Omura, eager to showcase his talents in the ring, is injured due to an accident, and it has just begun...
