"Fighting Spirit's" long-running narrative contains several major turning points. Ippo's initial major goal is to face his rival, Ichiro Miyata, in the professional ring. However, this is permanently thwarted after Miyata loses a match he shouldn't have, moving up a weight class and making a professional match between them impossible under normal circumstances. This forces Ippo to find a new motivation beyond his rivalry.
Ippo's journey sees him win the Japanese Featherweight Championship by defeating Takeshi Sendo in a brutal finale to the first season. He goes on to defend this title multiple times. A significant twist in his career is his first professional loss to Eiji Date, which denies him his first shot at the world stage and teaches him the vast difference between a national champion and a world contender. Later, Ippo's second professional loss comes against Alfredo Gonzales, a world-ranked fighter. This defeat is pivotal as it's the first in a series of matches that reveals the cumulative damage Ippo has sustained throughout his career. He begins showing signs of being "punch-drunk" (CTE), a condition where a boxer's brain is damaged from repeated blows.
The most significant plot development, which occurs in the manga long after the anime ends, is Ippo's retirement. After losing a comeback match against Antonio Guevara, he fulfills a promise to his mother and coach to retire if he loses again. This marks the end of his boxing career. However, his story doesn't end there. He finds a new purpose as a second and trainer at the Kamogawa Gym, where his analytical skills and deep understanding of boxing shine. This new role allows him to see the sport from a different perspective, and the narrative strongly implies that by shedding the immense pressure he put on himself, he may finally be developing the mindset of a true champion, leaving the door open for a potential, future return to the ring having finally understood the meaning of strength.