He was raised with his two parents, younger sister (Bai), and identical twin brother (Jie). They lived middle class average lives in a small, rural village.

As a child, his familial relationships were good, he was close to all of them. At this age, Jun and Jie were indeperable and indistinguishable in appearance. To tell them apart, you'd have to pay attention to their demeanor. Jun tended to be more quiet and stuck to what he was comfortable with while his brother was a bit rowdy and adventerous. In his social life, him and Jie were in the same social circles due to the lack of other kids his age in the village. Jun was well liked enough, but was viewed as the "inferior" twin due to his brother's reputation of being charasmatic and proactive. This was never said explicitly to the boys, but it was obvious in how their friends would treat Jun differently. Growing up, the friend's attitudes towards Jun began to sour as his hestitation to do activites with them such as exploring the woods and little acts of vandilism made Jun out to be labeled as a goodie two shoes and a scardey cat. Jun would stuck with the group despite feeling like an outsider because he wanted to continue to have a connection to his peers.

At around ten years old, a lower mooon attacked his village in the middle of the night. Demon occurances were not common in this country, and unheard of in rual villages such as this one. The demon into their home while the family was asleep and first targeted the twin's room. Initally believing the noise in the house was a robber, the boys woke up and hid before the demon entered. Jun hid in a closet while his brother hid under his bed. When the demon came into their room, he found Jie first and Jun had to watch powerlessly as his brother weakly fought for his life against the demon. Luckily, a Hashira who was sent on a mission after this moon rescued Jie before the demon could kill him. Jie ended up surviving the encounter, but suffered fatal injuries. The recovery for the external injuries alone took months, and in that time Jun had to deal with the backlash of his friend group. They blamed Jun for not stepping in and saving his brother, and claimed that it was his cowardice that he has shown time and time again that caused Jie to almost die. Even worse, he could feel that his relationship with his brother was waning since incident, Jie was unable to speak for most of his recovery, but he could feel resentment. It came to a point where he couldn't take it anymore and ran [UNFINISHED]. His parents tried to be supportive as possible and sent Jun on small jobs so he would at least be active instead of becoming shut in. This is when he met the town's painter on a delivery run, the painter was a kind, old fellow who was happy that Jun took interest in his work. Jun routinely visited the old man and ended up using art as a healthy outlet for the emotions he has held.

After recovering from the worst of the trauma, he wanted to make a change in his life. The painter encouraged him to try and explore himself and follow his passions, seeing potential in him as a person. Taking this advice to heart, when he turned thirteen, he began his training under a retired hashira for water breathing. He drove all his passion into training and honing his skills, he found water to be fairly natural for him. He likes to compare the feeling to painting and says he envisions himself making an art piece when he fights. Due to his determination and practice, he quickly climbed the ranks and became the new water hashira at seventeen.

Currently, he is a very powerful member of the hashira. It should be noted that he still suffers from claustrophobia, survivors guilt, and a touch of depression from the trauma. Though, he does a good job managing it and has found many healthy outlets to deal with his trauma. Despite this, he is not very open about it and most people do not know that he suffers from anything or has this history. He makes sure to avoid small spaces at all costs in order not to trigger anything that may alert anyone to his troubles. He cares about his image, and though he tells people that it is good to express themselves, go to therapy, etc. he does not follow his own advice. As a hashira, he feels it is important to hold an image of strength, somewhat emulating how he admired his brother when they were kids.

His relationship with his family is still fairly alright. He stays in touch with his parents occasionally but rarely reaches out to his siblings unless they initiate. He can tell that his sister pities him in her own way, and tries to constantly encourage him to come home to visit them. Meanwhile, Jun and his brother still have a very strained relationship since they have not really talked about the incident or have been given closure.

At some point, Jun has his arc and is able to speak to his brother and begin the steps to true recovery for the both of them. In the end, their relationship will mend and they'll be able to smile together like they used to.