Birth Date: November 23, 1973
Homeland: Tokyo, Japan
Gender: Male
Family: Hiroko Makunouchi (Mother); Kazuo Makunouchi (Father); Wanpo (Pet)
Occupation: Professional Boxer; Makunouchi Fishing Boat
Weight Class: Featherweight (Weight Limit 126 Pounds)
Height: 164 cm (5'5")
Reach: 165 cm (65")
Style: Infighter; Peek-A-Boo Style
Current Affiliation: Kamogawa Boxing Gym
Trainer: Genji Kamogawa
Specialty/Signature Blows: Liver Blow, Gazelle Punch; Dempsey Roll,
The Anti-Anti Dempsey Roll, The "New Evolved" Dempsey Roll (Dempsey Roll 2.0)

Ippo Makunouchi is the main protagonist of the series. He lives with his mother, Hiroko Makunouchi, and helps with the family charter boat fishing business. Ippo is a classic power in-boxer and is well known for his Peek-a-Boo style of boxing and hard punches which include three signature punches: a rib-cracking liver blow, Gazelle punch (an uppercut variant), and the Dempsey roll technique. His signature punches appear to be modelled after Mike Tyson, Floyd Patterson and Jack Dempsey respectively.

Ippo is bullied throughout most of his school life. After being rescued by Takamura, he ends up being brought to Kamogawa Gym, where he displays an explosive punching power. After seeing a video of Mike Tyson, he becomes inspired to take up boxing to feel reborn with strength. He soon proves himself to Takamura and Kamogawa, and starts on the path to being a pro boxer.

His Pro-Debut Match was against Oda Yusuke, He was largely regarded as a lazy and unmotivated boxer, but when his girlfriend threatened to break up with him, he committed himself to training. From the first time the boxers met, there was tension between them, as a misunderstanding led Oda to believe Ippo made fun of him. On the actual fight, Ippo seemed to have the advantage from the beginning of the match, but was saved by his coach from losing the fight due to a cut. Ippo managed a comeback by knocking Oda out with a series of jabs, thus winning the fight.