Yusuke was born into the Jiaharu family line during the New Years eve ceremony in the Iwakagure. His parents considered the date a blessing and believed their son was going to be a great doctor one day. Even at the start Yusuke stopped crying and started laughing shortly after birth. He grew up in his parents' clinic where the majority of the Jiaharu clan was living and had to deal with his mother off constantly and his father staying at home. However despite his mother not being around he enjoyed spending time with his old man and grew off him as he developed a similar personality to his father and uncle who was staying in the city until he could make a clinic of his own. He was sent to the academy one year after he came of age and was shy at first but became his usual self after he met Aya Kobaiashi in the playground when he was sitting by himself, he would later fall in love with her, and Yoshihisa Honda, who he developed a rivalry with seeing as the kids did not get off to a good start after Yoshihisa spilt water all over Yusuke's head by accident. They also had differing personalities where Yoshihisa was disiplined and serious; Yusuke was sarcastic and stubborn as well as lazy. They went through their academy days together and became great friends with Aya, eventually he warmed up and became Yoshihisa's friend too. He graduated the school at the middle of his class after recieving lessons from Aya and Yoshihisa with some help.
Their fondest memory was when Yusuke replaced Aya's shruikens with jelly donuts causing her to chase them. That memory would soldify the guys of the group and cause them to become better friends than before. They all were assigned to the same squad when Aya politely asked their teacher to do so, much to Yoshihisa's disbelief and Yusuke's protests. They failed horribly when their sensei had them try and catch him in a rock climbing contest and then made them try to catch bells of which Yusuke was tied to a metal pillar upside down. They eventually went through their missions on which Yusuke would always complain about the labor of it but stop to help those with wounds and use his medical ninjutsu, which he learned from his parents after getting a scrape on his knee, to help as best as he could. He was often called a smartass due to him being considerably smarter than most kids his age but being extremely lazy in doing so. However he was always up for some fun and games and costantly pranked their sensei. He also took on the bullies of the Iwakagure and attempted to make them stop picking on kids smaller than them but he frequently got his butt kicked and ended up getting saved by Aya, or Yoshihisa in some cases. His pranks often came on the leader of the village as well as when he once dunked a bucket of sour milk on his head when he was a kid.
As they grew older around the age of thirteen he finally started to see Aya as more than a friend, despite her occasionally giving him clues about how she felt about him, after he saved her from a rock falling on her. They hugged and looked into each others eyes but letting go and awkwardly walking away as Yoshihisa looked on chuckling at the new developements. He eventually started to go out with Aya, after getting his father's permission and gaining the respect of her father, and went on dates as often as they could. They were in love deeply despite of their age and thought it was ment to be. Yoshihisa approved of it himself but he could careless personally. As they went on they got into all sorts of arguements but kept dating. Yusuke was enjoying himself greatly and he always made new friends in the village. He was a talented medical jutsu specialist but his physical and ninjutsu skills left much to be desired.
As the Chunin Exams came along he was nervous and not expecting to be sent in there with Aya and Yoshihisa, who were both visably stronger than he was, and joked that he was the odd ball out but went anyway at his teacher's insistance. His uncle warned him about the dangers and he learned some more moves to help protect his team mates. As the first Exam came along he was put into the opposite side of the room from his team mates and when the rules were spoken he was truely afraid he might give up. He attempted to go throughit confidently but his courage nearly failed him but another ninja next to him slapped him upside the head and told him to calm down as he was attracting the chunin watching them. He calmed down and answered all of the questions he knew and passed when with all the others who did not flee or cheat. He cheered only to get clobbered by Aya who told him to stop over reacting. Yoshihisa backed that up as he was sure that the others would have trouble in the next challenge. During the off time between the exams Yoshihisa was taken by their sensei along with Aya. However Yusuke refused to train and instead went to his aunt's house who relocated to the testing spot. He learned more about himself and the ninja arts there unwittingly as his aunt tricked him.
As the second exam started he promised them they would win which Yoshihisa was unsure of seeing a lot of powerful ninja there. Aya back talked Yoshihisa on that and they started the course. As they went through it Yoshihisa and Aya had little chances of finding the scrolls when suddenly Aya was pierced by ten shruikens and four kunai all of them poisoned. The poison was immediate and caused Aya to scream in pain and fall to the ground writhing from it as she coughed. Yusuke and Yoshihisa looked on in horror as something strange to Yusuke unlocked in Yoshihisa he to was filled with something he had never had before. Killer intent and froze the enemies in place for a few seconds in those few seconds the ninja were brutally killed besides one who cut Yusuke's leg badly causing him to fall over. He crawled his way over to Aya who was barely still alive and the last things she told him were to tell her family she was sorry and she loved him and Yoshihisa like family. Yusuke was absolutely miserable as he cried and begged her not to go as he attempted to use his medical ninjutsu on her it was of no use her last act was to give him his first and last kiss.
Yusuke and Yoshihisa brought her body with them as they went through the forest, Yusuke patched up his leg as best he could, in silence they arrived to take the third exam as they bitterly mocked the man who appeared infront of them and her body was taken away solemly from Yusuke's arms. Yusuke was deemed unable to compete by other ninja and he needed time to recover however Yoshihisa, who had deactivated his sharingan, had fought on only to be defeated by a sand shinobi. About three days later the mourned the loss of their female companion and Yusuke fell over it and wheeped bitterly. Yoshihisa went over and told him that was his fault for not being aware enough at which Yusuke lashed out at him. Yusuke blamed himself and got up and yelled into Yoshihisa's face causing a fist fight to occur amoung them. They fought for twenty minutes with nothing but punching next to Aya's grave and eventually settled down right next to her grave where a flower laided down unhindered. Yusuke then promised never to let this happen again. Yusuke then pronounced that they would become sworn brothers here and now with the pact addition being that they would never let this sort of thing happen again. Yoshihisa agreed to that and together they oath of brotherhood
there on the spot.
After this they went back home where Yusuke worked as a medical nin for the local hospital with his father who tried to cheer him up but for a long time Yusuke was miserable. However Yoshihisa was rarely seen by him as they were both in different areas most of the time. Yoshihisa had decided to go and coutinue being a ninja where Yusuke had decided to stop it for awhile and take a break. In that time Yusuke become stronger and more quick but still had barely any physical skill relying on the strength of his Medical jutsu which allowed him to quickly dispatch enemies. However Yusuke's philosphy on death never changed and he was truely scared of himself when he woke up and saw the killer intent in his eyes. He eventually went back to his normal-self but only after extensive talks between him and his mother and father.
Yusuke eventually joined back up with Yoshihisa before the chunin exams and decided to keep working with him. Along the way he decided to fight in the chunin exams again with Yoshihisa's level gap far higher than his and a new kid was there too. Despite Yusuke not liking the new kid, Hyuki, he dealt with him like he would anyone else but there was a certain animosity towards him and Yusuke mentally rejected him. When they passed the first test it was typical and they waited until the second started. There Yusuke was worried as this was where it had all started. Again they went through the forest but this time it was fairly simple and the trio crushed the enemy genin team with ease. However it all fell apart when Hyuki was stabbed by a explosive tag on a kunai by accident as a Amekagure team attacked them. The boy was killed instantly causing a mental breakdown of Yusuke and the frustration of Yoshihisa as their oath was broken at the promise. They buried the boy there and moved on to the third round where Yoshihisa was able to completely crush a Takikagure ninja.
Yusuke won in four minutes after disabling his enemies legs and knees. Yusuke was now barely holding on when the leader of his village told him to stay strong and told him a story which brang Yusuke back to the real world. Yusuke than proceeded to fight back against the enemy in the fourth round, a byakugan user from the Hyuga clan, and beat him but just barely but disabling the enemy's eyes than knocking him out with a neck shot after losing all feeling in his legs. Yusuke bailed out saying that he was unable to fight but was promoted to chunin for his emotional fights and his skills as a medical ninja. Yusuke felt like it was a worthless promotion but was put on Yoshihisa's team as a skilled medical professional and has been there since.