To people that asked a couple of chapters ago why such decision is fallen to middle school boy, the hospital has not been able to contact his uncle due to the nature of his work and he was the last relative left with connection to Hajime's sister, Mio, as the same accident already took their Mom and Dad's lives. I still think Hajime saying "Please let her go. She doesn't like being in pain" is really soul-crushing to read.
(Oh, specific nature of his uncle's work would come back to be beneficial to our leads later, too)
After that, yeah. His uncle once heard the news did everything he could to bring Hajime back to his feet. It feels like he is the 'underperforming' in class for the first 3 chapters, but Chinatsu will quickly learn that Hajime's 'well-put together' is quite an understatement. Our man takes quite a lot of subsequent actions you don't really see normal high schooler do to get together with her.
At later stages, Chinatsu often wonders if she does enough in the relationship to be of equal to him, but again, in high schooler's perpective, Hajime's influence on Chinatsu also make her quite ahead of her peers in a lot of ways, too. They really suit each other at the end of their arc before the story shift focus to their peers.