Birthday: August 14, 1975
Homeland: Japan Tokyo,
Occupation: Professional Boxer, Makunouchi Fishing Boat worker
Weight Class: Featherweight
Height: 168 cm (5'6")
Reach: 168 cm (66")
Style: Out Boxer
Stance: Orthodox Stance
Current Affiliation: Kamogawa Boxing Gym
Trainer: Shinoda

The most recent addition to the roster, the charming Manabu has a prodigy's talent and was the captain of his high school's boxing team. Cheerful and a lover of bad puns, Manabu is a fierce outboxer with extremely high speed and reflexes and whose fighting style is uncanny in its resemblance to Miyata's. His most powerful technique is a furious hail of mid-power blows known as the Hedgehog or Porcupine, which was employed in an East Japan Rookie Kings showdown with his longtime nemesis, Kyosuke Imai. Outside of boxing, Manabu is employed as an assistant at the Makounouchi family's fishing business. Itagaki's character is based on former world champion Oscar de La Hoya for his prodigy-like natural ability and good looks, whom Itagaki has admitted to idolizing in the manga.

He is a Featherweight out boxer renowned for his speed and genius boxing talent. His trainer is Shinoda Tomoyuki. He, along with Makunouchi Ippo, Takamura Mamoru, Aoki Masaru, and Kimura Tatsuya, round out the core members of the Kamogawa Boxing Gym.

Itagaki originally tried out and prevailed at many sports, but when he tried boxing he came across Imai Kyousuke and was defeated by him 3 times. In order to defeat him no matter what, he skipped college and instead joined the Kamogawa Boxing Gym, where his idol, Ippo, trained.

After Umezawa Masahiko retired from the Makunouchi Fishing Boat in order to pursue his own dreams, Itagaki took over his job and started receving the same kind of work training that Ippo goes through. He achieved revenge on Makino Fumito, who had defeated him in his debut match with a foul, in the opening round of the East Japan Rookie Kings. At the finals, after a tough fight with Imai, Itagaki captured the East Japan Rookie King title and seemingly tapped into his true fighting potential; his speed, reflexes and timing are now said to be at genius levels.

With Ippo relinquishing his title to take on the world, a rematch with number 2 ranking and long time rival Imai was scheduled to decide the new JBC featherweight champion. Although it was a title match, because Itagaki had conquered his goal in the Class A tournament to beat Ippo's KO times against Saeki and Karasawa, as well as because he had defeated Imai before, he went into the match extremely overconfident. With a dazzling strategy, Kyousuke trapped Itagaki in the corner and wore him out with various body blows, eventually KOing Itagaki in the first round. Afterward, Itagaki acted like a good sportsman, but in truth he was disappointed in himself for letting down Ippo and dropping Date's baton.

Current Record
Rank: 1 (JBC)
4: (OPBF)
Total fights : 14
Wins 12
Wins by KO: 10
Losses: 2
Championships: East Japan Rookie King