Kiku and Ryuji take over their late father’s ambition of becoming a boxing champion. As his sister trains him, Ryuji progresses physically and mentally and he finally meets his destined rival, Jun.
As the curtain rises on the Junior Boxing World Tournament, a grand conflict unfolds between Ryuji’s team and champions from many nations. A life and death struggle begins, with the title of World’s Strongest on the line. Which country’s flag will end up flying higher than the rest?