A boy with a quick temper, almost always found mistreating his younger sister, Kana. Whenever he feels upset, his first reaction is to hit Kana. Despite this behavior, it's evident from the start that he does care for her, as he prevents Kana from "playing the game."
A later chapter reveals that Jun's mother died giving birth to Kana, which explains his resentment towards her. During Kanji's story arc, Jun admits to him that he did not sign the contract. During Kana's fight, she discloses to him that Tanaka, who is about to die, is actually his biological mother. Jun was the son of a delinquent student (later revealed to be Tanaka) and an unknown father. The Ushiro couple, who at the time had no children, decided to adopt Jun. After Kana's and Tanaka's deaths, and witnessing the remains of Tanaka's plane along with her grieving husband and daughter, Jun asks Dung Beetle to enlist him.
In the anime series, not only is Jun a pilot, but it is also revealed that he is the orphaned son of Misumi Tanaka and a deceased Yakuza heir. After Misumi's death, Tamotsu informs him about his origins. After Kanji's battle, Koemushi asks him to convince Kana to sign the contract in exchange for becoming the final pilot, who according to the rules, has a chance to survive if victorious. However, Jun decides not to involve Kana in the contract and asks Machi for help. After Machi's victory, Ushiro demands Seki to let him become the next pilot and destroy Zearth after winning, thus relieving both of the successor's duty. After a grueling 30-hour battle, Jun manages to defeat his enemy and ultimately save the Earth.
