That was a solid first chapter!
What impresses me the most about Kento Terasaka is his ability to infuse his characters with struggles in a way that feels personal before it feels plot-forwarding. In my opinion, this is exactly what mangaka should strive for when writing sports series, in which all narrative weight derives from the readers identifying with the characters. I think this also the reason why I have not enjoyed Drawn to the Fire as much as I wanted to.
To achieve this, I believe a writer must have a strong conception of a character's drives, and avoid revealing these drives unnaturally. That is quite difficult: it requires a balancing act of giving readers enough understanding to latch onto and making a character feel realistic and therefore impossible to fully comprehend. Characters must act consistently as if they were a real person, with their actions subtly betraying a bit of who they are.
This time in particular, I suspect Kento Terasaka poured a lot of his own emotions into Miharu. Nobody who seriously chases their dreams fears defeat for itself; however, repeated defeats create self-sabotaging and transforms one's motivation from running after success to avoiding another failure without them even realizing. The pursuit becomes burdening, and when quitting becomes an option, it disturbingly almost feels like an opportunity to find solace. I'm sure Terasaka-sensei went through this himself after Green Green Greens' cancellation, and managed to get back on his feet to try again.
Miharu's characterization is great. I can't help but wonder if part of the reason why he hesitated so much is because he is Haruka's only caregiver, and he does not want to leave Haruka without any family. When Haruka jumped, it eased Miharu's anxieties because Haruka would be happy if he did well too. Not to mention the more obvious point of it demonstrating to him that fears can be overcome.