Koushiro Izumi (泉 光子郎 Izumi Kōshirō) is a character in the anime and manga Digimon. He is given the nickname "Izzy" in the English versions. His name is romanized as "Kohsiroh" on the image files on Toei Animation's Digimon website.

He is the partnered to Tentomon. Izzy is a computer nerd and spends all his time trying to figure stuff out on his Pineapple laptop. He played on the soccer team with Sora Takenouchi and Taichi "Tai" Kamiya (Taichi Yagami in Japan). Izzy lives with his adopted parents. Although he once has a complex about it, he finally hears the truth from them about the adoption and accepts them as his true parents. He is the bearer of the Crest of Knowledge.

Prelude to Digimon Adventure

Digimon Adventure

Digimon Adventure: Our WarGame

Between Digimon Adventure & Digimon 02

At May 2000, Izzy arrives at the Digital World and gives up his Crest-power to free the Sovereigns. As a result, Tentomon loses the power become Mega Kabuterimon.

Digimon 02

Although he grew, he's still short compared to the other kids now as tall as the new team. Koushiro seems to have a lot of free time and often stops by the computer club at the elementary school to help the new DigiDestined in almost every episode. He's still into computers and is curious about the D-3 and other items the new DigiDestined have access to.

Digimon 02: Michi E No Armor Shinka

Digimon 02: Diaboromon's Counterattack

Digimon 02: Series Finale epilogue

By the year 2027, Izzy sets up a research team to study more of the Digital World than what the human population already knows. He has a daughter.