Aragaki's backstory is half nightmare fuel and half tear jerker. A skilled boxer and Nanbu's student, he volunteered for a war only to have his legs blown off by an IED while believing he was rescuing a child from a crumbling building. He attempts suicide only to have his Pocket Protector remind him he still has his coach and his boxing friends back home waiting for him. Upon returning from the war, he discovers said boxing club has been shut down and Nanbu has disappeared off the face of the Earth, having never bothered to so much as contact him. Even his new life as a boxer with the VA turns out to be time-limited because his prosthetic legs can't handle the stress, meaning he never had a realistic shot at Megalonia.
On a related note, Aragaki's conversation with Nanbu in the locker room after his match with Joe.
Aragaki: I'm gonna move on. For me... (tearing up)...tomorrow starts today. I made it this far on these legs. That's... that should be far enough, shouldn't it, coach? (continuing to tear up)
The aftermath of Joe and Yuri's fight in the first season. In the bonus episode that details what Yuri's up to after the final match, he mentions to his coach Jimmy that he can no longer stand in the ring.
Nomad
Episode 1
When Joe buries the dog. Especially considering that the stray dog’s design calls to mind the one symbolising Joe from the season 1 OP.
Seeing how far Joe has fallen in the Time Skip, addicted to pills and drinking, aimlessly driving around with his identity hidden, and a psychological manifestation of the deceased Nanbu following him. Him grasping desperately to reach the bottle of pills that fell out of his pocket after Chief knocks him to the floor at the end of the episode is heartbreaking.
When Chief dies in season 2. He just won the tournament and got the money that he needed to buy the land for the residents of the Casa. He'd literally achieved his goal, and then he dies before he gets to see it through all the way.
When Joe finally lets go of Nanbu. After hearing Mara's story of how Chief became addicted to painkillers and also used alcohol to cope with and punish himself for the death of his son, Carlo, Joe suffers symptoms of withdrawal. Joe and the ghostly version of Nanbu talk for a minute, and Joe holds out his hand, asking Nanbu for his help. Joe doesn't get a reply, but instead, the sun streams through the wooden boards in the window of his trailer. He stares at his hand for a moment, then relaxes and holds himself. Joe was finally able to let go of Nanbu and process the pain that he'd been running from.
Comparing the thriving success of Team Nowhere’s gym in the past, to seeing it in the present, destroyed by the typhoon and everyone scattered.
The Deliberately Monochrome flashbacks. Seeing the fallout from Nanbu’s diagnosis, Joe running from dealing with his mentor’s almost certain mentality by focusing on winning a boxing match, and Sachio’s dismay that Joe isn’t spending time with Nanbu in his final days. All coming to a collision in his loss at the exhibition match to Liu, Nanbu dying before Joe could make it, and Sachio angrily telling Joe to leave and never come back.
Mac and his family’s heartbreaking reaction upon discovering the truth about the BES, and confronting Sakuma, who points out that without him, Mac would never be where he is now. Seeing him stumbling around, drunk, throwing bottles at his poster, calls to mind Joe at the beginning of this season.
When Joe sees Chief during his fight with Mac, echoing the promise they had made to each other before Chief’s untimely death.
