Life gets pretty boring when you can defeat every villain with just one punch. Nothing about Saitama passes the eye test when it comes to superheroes – from his expressionless face to his bald head and unimposing stature. Yet this average-looking guy has a problem that is anything but average – he simply can't find an opponent strong enough to challenge him!

At the martial arts tournament, Suiryu from the Dark Martial Arts shows promising strength. However, outside the stadium, a large number of monsters are pushing the heroes, even Genos, to their limits! Inside, unaware, Saitama approaches his fight against Bakuzan.