Koushiro "Izzy" Izumi
Koushiro Izumi
Brief information
First appearance: Digimon Adventure
Partner: Tentomon
Status: Alive
Date of birth: 3th May 1992

Koushiro "Izzy" Izumi, 18 as of Book Six, is one of the Original Seven (or Eight) Digidestined from Digimon Adventure. He is by far the smartest Digidestined ever, and has proved to be a great aid to the group in overall.

His partner is Tentomon. Izzy is a computer expert and spends a large fraction of his time trying to figure stuff out on his "PiBook" laptop. Izzy lives with his adopted parents. When he initially found out that he was adopted, he began to subconsciously distant himself from his parents and focusing on his computer. The issue is resolved when his parents come forward with the truth and he accepts them as his true parents. Izzy would often says "Prodigious!" in the old days, but still continues to use the praise on occasion.

Prelude to Digimon AdventureEdit

He saw the battle between Parrotmon/Greymon, resulting in him becoming a DigiDestined. Izzy's real parents died in a car crash, and Izzy's adoptive parents were asked to take care of him. He heard he was adopted on a night when he couldn't sleep.

Digimon AdventureEdit

Koushiro's nickname, Izzy, actually came from Tai. Once, when Koushiro tried to explain something to the group, Tai did not understand and called Izzy anything but easy to understand. The others found the rhyme with Koushiro's surname rather amusing, as was the fact that Tai had noted. Thus, from then on, everyone called him "Izzy". Even after Koushiro started to simplified his terms to allow his friends to understand him, they had gotten so used to calling him Izzy that they left it that way. Izzy of course didn't mind, for it showed that they were still close friends.

Izzy is the computer whiz of the group, and the most curious of the Digital World. He often prefers to be alone. Once in the Digital World, Izzy develops an "alien theory" and has a low opinion of the Digimon. For instance, when his partner, Tentomon, hears about Izzy’s alien theory, he asks, "What mystery is there to me? I am who I am." When the DigiDestined enter a factory, Izzy finds a large battery and enters. He wipes away a part of the hieroglyphics on the inner wall, causing the factory to stop production. Izzy becomes the first to realize that everything, even the program, is living in the Digital World.

Izzy’s skills with the computer, however, soon prove to be extraordinarily useful for the group. During the battle against Andromon, Tentomon suggests that Izzy reenter the program that activated his Digivice. When Izzy retypes it in, Tentomon digivolves into Kabuterimon and defeats the black gear in Andromon. When Mimi and Tentomon run into a maze, Izzy pulls out the map and locates Mimi’s location. He then directs her out of the maze.

After the defeat of Devimon, the DigiDestined are sent to the continent of Server to defeat Etemon. While they are in the capacity of Piximon, Matt and Izzy see that their tags are glowing. They sneak out and find their crests; Matt receives the Crest of Friendship, while Izzy receives the Crest of Knowledge. Izzy’s curiosity and deductive reasoning comes in handy once again; when Datamon captures Sora, he is the first to theorize that Datamon is still inside the pyramid. Tai and Izzy rescue Sora. Etemon learns of their presence and goes down there to destroy those kids. In the final ensuring battle, Greymon successfully digivolves into MetalGreymon and defeats Etemon. Tai and his Digimon are sucked into the Real World; during their short stay there, Izzy sends a frantic transmission, warning Tai not to go back to the Digital World.

However, Tai reenters the Digital World anyway, because he knows that he must restore the balance between the two worlds. Izzy runs into Vademon, who tricks him into giving up his curiosity and regresses him to an accepting mind that does not question anything. Tentomon frantically tries to get him back to no avail; he slowly reverse digivolves back into Motimon and Pabumon before Izzy snaps out of it. Izzy gets his tag and crest and his curiosity back. In the ensuring battle, Kabuterimon digivolves into MegaKabuterimon and defeats Vademon.

During the search for the Eighth Child, the DigiDestined pursue Myotismon into the Real World. Gennai loads a couple of programs into Izzy’s laptops that gives him much information. The first program tracks the movement of Digimon; Izzy sees Raremon attacking Tokyo Bay and rushes out there with Tentomon to stop him. The second program puts up a digital barrier, which stops the Bakemon from taking Izzy and his parents away. Gennai also tells Izzy that the source of Myotismon’s power is in the Fuji TV station and describes the prophecy to him. The prophecy aids them in defeating VenomMyotismon; when Izzy reads the prophecy out loud (it took the Digidestined some time to figure it out), the group follows its lines. Angemon and Angewomon hit Matt and Tai with arrows of hope and light, which leads to Agumon and Gabumon warp digivolving into their Mega forms, which is of tremendous aid in the battle.

During this saga, Izzy’s parents reveal to him that he was adopted. Izzy’s real parents were killed in a car accident, and his father’s distant cousin adopted Izzy. Izzy also reveals that he found out when he overheard a late-night conversation, and says that he retreated into computers to try to forget about what he had overheard.

Izzy’s computer becomes a more valued asset as the DigiDestined battle the Dark Masters. Before, their Digimon partners used to describe the information about the various Digimon that they encountered; now, Izzy has loaded a database of Digimon profiles. When a new Digimon shows up, Izzy names and describes the characteristics to the rest of the DigiDestined.

In the last battle against Piedmon, Izzy was turned into a key chain. After Apocalymon was defeated, Izzy calculated that, because one day in the Digital World equaled just one minute in the Real World, the DigiDestined could stay in the Digital World for 118 years. However, Gennai tells them that the time distortion was fixed with the defeat of Apocalymon, and that the solar eclipse would seal the barrier for an indefinite amount of time. Izzy says goodbye to Tentomon, thanking him for being a good friend.

In May 2000, Izzy arrived in the Digital World and gave up his Crest power to free the Digimon Sovereigns. As a result, Tentomon lost the power to become MegaKabuterimon.

Our War GameEdit

In Our War Game, Izzy is the one who first discovers a digi-egg infected with a computer virus on the internet, and then rushes off to alert the others. He comes over to Tai's house to watch the battle unfold. He is deluged with the number of e-mails coming in, trying to frantically ask the other people to stop sending them, as their lag is slowing WarGreymon and MetalGarurumon down. After the two of them DNA Digivolve into Omnimon and take out all of Diaboromon's clones, however, the remaining Diaboromon is too quick for Omnimon, always jumping away just as Omnimon spots it. Izzy finally comes up with a plan, forwarding all of the emails to Diaboromon to slow him down. Omnimon manages to destroy Diaboromon just seconds before the nuclear missiles would have hit Japan. During the course of the movie Izzy appear's to be very appreciative of Mrs. Kamiya's cooking.

Digimon Adventure 02Edit

Izzy, though being a genius, decided to stay in elementary school along with his friends instead of progressing ahead in his studies. After his time in the Digital World, Izzy devoted his time to studying a way to return and meet his partner again. After the older generation progressed to high school, Izzy stayed on in elementary school to keep Kari company so that she wouldn't be alone when TK moved off with his mother. Fortunately, T.K. soon returned, allowing Izzy to go to high school in peace.

Three years later, Izzy is now in high school and was a president of the Computer Club. Izzy continues to play his technical role; he monitors the Digital World and alerts the new DigiDestined to upcoming troubles and problems. Izzy devises the plan to invade Ken’s base; with Cody’s information that a pipeline will cross paths with Ken’s base, he directs Agumon and Gabumon to create a diversion. Later, when Ken’s base is about to explode, Izzy tells them the problem and when the warp is back to normal.

With Willis from America, he also figures out that the new Digivices have three new functions, and dubs them the D-3s. Lastly, after school gets out, Izzy theorizes that the power of the D-3 is what really opens the gate to the Digital World. This theory proves to be correct, and gives the DigiDestined the ability to open up ports at any time and any location, rather than being limited to simply using the school’s computer lab to move in and out of the Digital World.

Revenge of DiaboromonEdit

During his return, Izzy still was responsible for the planning and execution of the attacks on Diaboromon. He was the one who gathered all the DigiDestined (including Mimi Tachikawa, who flew in from America) to help defeat Diaboromon and stop the havoc it wreaked on the net and the real world.


In Dimensions, Izzy eventually gains the ability to Biomerge with Tentomon to the mega form Raijinmon. Even without his new power, Izzy has a lot of insight to offer at various points in the series and continues to maintain his role as one of the smarter human partners.

When the second generation of Digidestined progressed to high school, Izzy felt out of place being in a lower grade, so he decided to join the older generation both there and in university by simply requesting so, on the basis of his high intelligence and academic performance, way beyond many of his peers. He currently resides with his partner, Tentomon, with the other older generation of Digidestined at the File Apartments.

During the events of Book Seven, Izzy is the one who sent out the mass e-mail telling the tamers to run to the park to escape the armed forces sent by Rayleigh Thompson. Unfortunately, Rayleigh also had access to the e-mail and staged a trap at the location. Still, they managed to flee to the safety of the Digital World.