Born in 1989, 14 years old, a 7th grader at Odaiba Junior High. He is brilliant and the bearer of the Crest of Knowledge. He possesses his original Digivice but not a D-3. His partner is Tentomon. While he is an expert with computers, he struggles with English conversation, though he can read and write it well (as coding would be impossible otherwise). He is not cold toward those he trusts, but he can be overly intellectual and unsocial. He is polite to everyone, yet maintains a strong tendency to keep others at a distance. He gets along well with the other children he traveled to the Digital World with. He loves oolong tea.

Joe Kido (9th grade, born 1987); Sora Takenouchi, Tai Kamiya, and Matt Ishida (8th grade, born 1988; Matt is T.K.'s older brother and of mixed French-Japanese descent); Mimi Tachikawa (7th grade, born 1989, currently attending middle school in America); Yolei Inoue (6th grade, born 1990); Kari Kamiya (Tai's sister), T.K. Takaishi (Matt's brother), and Davis Motomiya (who likes Kari) (5th grade, born 1991); Cody Hida (3rd grade, born 1993).

An Insectoid Digimon with a witty sense of humor. He is social and kind to others, often offering advice or reality checks to Izzy.

A kind woman and Izzy's adoptive mother. Like her husband, she is a wonderful parent who understands Izzy better than anyone. Before adopting Izzy, she suffered the loss of her biological son to illness as an infant. She used to worry about Izzy not opening up to his adoptive parents or others. During Myotismon's invasion, she even broke down in tears, begging Izzy to stop clinging to his computer and run away. Though not his biological mother, she loves him dearly. After revealing the truth of his adoption and further improving their relationship, she has become a doting mother who showers her son with affection. When she first met Tentomon, she thought he was a doll and fainted from the shock when he spoke, but she has since grown close to him, even calling him 'Tentomon-kun' or 'Izzy's friend'.

A scientist and Izzy's adoptive father. He is a supportive father who understands Izzy deeply. He was a distant relative of Izzy's biological parents, who were mathematicians. Following the death of Izzy's biological parents in a car accident and the death of his own biological son, he adopted Izzy. He initially kept the truth hidden to protect Izzy from being hurt, but he confessed everything after the Myotismon incident. Izzy already knew the truth but wanted to hear it from his father's lips, and this moment served to resolve the lingering emotional distance between them.