
This honestly made me angry like that guy is a total jerk and even if he regrets being mean or hitting the guy doesn't change what he did. While reading this all I wanted to do was punch the guy in the face ヽ(`Д´)ノ

I think Hamura is insensitive and self-centered..
First, bec. he knew he has THE talent.. he actually do not see ORDINARY people's point of view.. that explains his comment about "the envy of those without real talent" on page 5 of ch.2.. this phrase tells the truth,yes but at the same time, shows about how he looks down on these people..
although in the shadows, he also work hard.. but that doesn't excuse him of being lazy on practice time or his blatant disrespect of rules of the track club..
Second, he has quite an achievement and maybe he has begun feeling the peer "pressure".. because, everyone expects something from him.. that's why "continuing track" became a sore spot to him.. Jin admires him and helped him a lot whether it is training to improve his time or to reduce injuries.. But because Jin encourage him to do track.. Hamura thought Jin is just like others who only see him as a track athlete and nothing more.. It is his own assumption and he became rude whenever it is the topic of their conversation..Thus, his remarks became more and more insensitive and rude.. I understand the pressure he must have felt that led to his insecurity BUT with great power comes great responsibility..(lol) He obviously enjoy special treatment because he's talented, yet he refuse to acknowledge that people naturally and normally will expect something from him bec. he's talented..
If this is not being a jerk, i don't know..

Here's the thing.
Hamura has been praised as a prodigy. He was isolated, depressed, upset how people treated him because he thought ALL they cared about was his ability to run and not himself. He was on the edge of quitting running for a while and then he met Jin.
He fell hard for Jin, but due to his social issues he didn't understand when he was saying hurtful things. It wasn't intentional.
But it was intentional the way he treated other people who only praised his skills. He saw them as vapid hangers on who only wanted to use him. He's not wrong there. Not fully at least.
Jin on the other hand...As much as he loved Hamura he also wanted to 'save' him. He loved the Hamura who ran (but not just that). He saw Hamura's talent and saw it as a waste if Hamura quit. And he kept subtly trying to push Hamura to continue running.
Jin was leaving and I think he knew about it for a while and was planning on breaking up with Hamura because he was going overseas and the issue with long distance relationships. That is why he left in the middle of his 3rd year since our school years start in the Fall instead of the spring.
Jin wanted Hamura to continue running. He didn't want to be the one who broke Hamura's ability just because he was leaving him. So as he was breaking up with Hamura (who had no idea why and thought they were happy together and planning on going to uni together) he brought up the running.
Hamura had a breakdown. The love of his life was leaving him and he didn't understand why but then Jin brings up running which Hamura has started to hate and he 'realizes' oh he only loved me because I can run. And then he wants to 'hurt' Jin like how Jin just hurt him. So he wants to destroy what it is that Jin loves which was his running skills.
I think Hamura was planning on slicing his ankle to cripple his ability to run. Jin realized this and tried to stop him using his body to block it. Possibly thinking his shoulder or back would get hit. Instead it was his eye and Hamura basically had a blue screen of death moment and froze in horror at what he done.
Then Jin left with no further word to Hamura who took it to mean that Hamura hurt Jin so badly that he hated him so much he didn't want anything to do with him anymore. Which is why Hamura obsessed about Jin and tried to fulfill Jin's wishes of him continuing track (but switched to pole vaulting since he HATES running) in the hopes of meeting Jin again to make amends.
That's why I don't think Hamura was a jerk. If anything, Jin attributed to thinks by keeping silent about his university plans and leaving. As well as his worries about their relationship. Their youth, insecurity, and miscommunication attributed to them falling apart and the injury. They are BOTH culpable.
Im SAADDDDDDD