Umezawa started out as the leader of the crew that bullied Ippo in high school, complete with the pompadour hairdo that screamed delinquent. Once Ippo turned pro and started making waves as a boxer, though, Umezawa did a complete 180—he became one of his biggest fans. By graduation, they'd actually become genuine friends, even if Umezawa was too proud to say it out loud at the time.
The high school version of Umezawa came across as a real jerk who refused to acknowledge that Ippo meant anything to him. After graduation, he mellowed out considerably, ditching the delinquent act and becoming way more laid-back and funny. Throughout high school and his years working on the Makunouchi Fishing Boat, he showed up to basically every one of Ippo's fights, usually sporting a handmade support headband and basically serving as his one-man cheering section.
Once Umezawa left the fishing boat to pursue manga as a career, Itagaki Manabu filled the gap he left behind. Whether he's kept attending Ippo's matches since then is anybody's guess. Fans have noted that Umezawa functions in some ways as a self-insert character for mangaka Morikawa Jouji.
Content compiled by AnimeList.moe from publicly available sources.
