Jonathon is Izzy and Kichi Izumi's son. He has his mother's looks and inherited his father's knowledge and love for computers. Like Izzy, he carries his laptop everywhere and is almost always on it or doing math problems.

Being very smart for his age, he can be very mature and can sometimes shut himself away from the world and bury his head in his school books. But with his brains he is a valuable member of the team. Jonathon is fasinated by the Digital World and spends many free hours with his father at the research lab learning more about Digimon.

Jonathon is often teased and called a nerd due to his love for school and computers. Because of his mature nature he can sometimes forget he is just a kid and doesn't join in on fun activities. He is mainly the reciever of Dawn and Dan's pranks. This adds to his urge to be alone with his computer and books. But as the group spends more time together, his friendship with the others grows stronger.