|“||Shall I level this area with my Meteor?||”|
–Izumi, to Miwa, 
Izumi is a boy of average height. He has neck-length dark blond hair, and also golden eyes. When he is in trigger mode, Izumi wears a black long coat with thin red stripes on it and a Border emblem patch on his left sleeve, just like the rest of his Squad.
As shown in the manga, Izumi is a reckless person. He wanted to raze the whole battlefield with Meteor in just to lure Arashiyama Squad out. Tōma also said that Izumi always comes up with harsh ideas. However, this personality doesn't always show up, and he is actually quite intelligent and a good strategist. Izumi is a humorous person, often making jokes whether it be casual or in battles. He is slightly immature when he is around his friends.
- He likes fried prawns, croquettes, oranges, and using Full-Attack.
- He is the one who discovered the composite bullets.
- In Japanese, his name Izumi (出水?) means Flood and Kōhei (公平?) means "Fairness" or "Justice"
- He ranked fifth in the 1st Valentine's Day Ranking and first in the 2nd Valentine's Day Ranking.
- World Trigger Manga and Anime — Vol. 4 Chapter 30 (p. 3) and Episode 15.
- World Trigger Manga — Chapter 58 (p. 19)
- World Trigger Manga — Vol. 24 Character Profiles
- World Trigger Manga — Chapter 122 (p. 7)
- Daisuke Ashihara: Q145: Is Ninomiya-san the one who created composite bullets? Is it Izumi? Or an engineer? A: Izumi tried it out on some kind of impulse and it worked. That is why he is called ‘genius-like’ and ‘bullet idiot’.
Source: Border Briefing File, Page 304, Question 145
- World Trigger Manga — Vol. 5, Volume Extras
- World Trigger Manga — Vol. 11, Volume Extras