Haruki first came across Akihiko at university overseeing an argument he was having with other people. His initial reaction was Akihiko was a tall guy and scary then making eye contact, Haruki got something like the chills. When they first met, Haruki considered him more hostile at first, describing him as being ten times more unapproachable. Noticing Akihiko's violin case, Haruki figured he was a music major.
One day in a lecture theatre he found himself seated right next to Akihiko who was passing him the class syllabus and stunned at this, Haruki only thought his profile was so hot, he could stare at him forever. Ignoring a message on his phone, it was around 13.15pm that day where Haruki made the fateful decision to ask if Akihiko played the drums after noticing his snare. As he did so Haruki contemplated that it was the first time in his life he stared at another guy's face so intensely, the light hitting Akihiko's eyes made them look even brighter.
That winter they had gotten over the bumps and met up with him and Ritsuka to form the band. Haruki fell in love with Akihiko and it has been his prayer for something to happen over the two years he has known him.
Haruki is two years older than Akihiko and they go to the same university together and are in the same band. They are close, taking breaks together and discussing matters such as Haruki saying that Akihiko knew full well why Ritsuka wanted to join the band but still asked him.
He is seized in a headlock by his band member after he asked Mafuyu if he had ever been in love. At first, it is shown the Haruki has strong romantic feelings for Akihiko and eventually becomes mutual after Akihiko cuts ties towards his on-and-off-again boyfriend, Ugetsu. They have agreed to keep their relationship a secret for Mafuyu and Ritsuka because of fears from backlash from Ritsuka. Akihiko is also the reason why Haruki grew his hair out in the first place and it is often complimented by him.
Haruki and Akihiko have a great complicit, so they can understand each other with a single glance; in fact they share a lot of looks on and off the stage.
He first saw Ritsuka and regarded him as a child prodigy on guitar. Seeing him walk by after a performance, Haruki instigated talking to him. Haruki considered Ritsuka a very confident guitarist and pretty easy to understand. Observing him arguing with his bandmates, Haruki considered it a waste and if Ritsuka were in his band he would give him a lot more freedom however Haruki felt he could not convince Ritsuka to join a band by himself without a drummer. Also considering him cool and giving up on the idea at one point, Haruki still remained determined to recruit Ritsuka into the band and was successful where they formed The Seasons together.
Haruki works well with Ritsuka, practicing bass guitar and suggesting music style for him to try. Haruki joins in Akihiko's lighthearted teasing of Ritsuka such as saying he was a good boy for asking them if Mafuyu could come again to watch them play.
He is supportive of Mafuyu, allowing him into the studio when he was waiting outside by himself and encouraged Mafuyu to share what he has learned.
Mafuyu formally joining the band was in Haruki's mind, yet time was afforded until Mafuyu was more comfortable playing the guitar.
Haruki was the first person Mafuyu gave contact details to telling him over email that he had an interview for a part-time job.
Yatake is close friends with Haruki as they are from the same film major and classmates. In more than one occasion, he has shown that he is concerned about Haruki’s feelings and state of mind.
Though he lives alone having moved to Tokyo from his hometown, Haruki's family includes his parents and an elder sister.