No offence, but no no no no no. Please let him not marry Akari. She should also not marry Rei's school teacher. Look these guys are great characters but too old for Akari (and yes I noticed that at least in manga's it's not much of an issue when someone is 10 to 15 years older.) I don't mind age difference relations but at a certain point I think, nope. Sure it's not that bad, Akari is like 22-23. Those guys are 36+. If I remenber correctly they are the same age. I remember a dialogue where his teacher tells Rei they're the same age.
Do I want her to get a good relationship in the end? Hell yeah she totally deserves it, but not them please.🥺
No offence either, but relationships with age difference of 15 years do happen in real life.
Speaking of Hayashida and Shimada as potential partners for Akari, Rei did discuss this at some point in his monologue chapters ago: Hayashida is sincere and can be Akari's anchor when she's lost, but his income as a teacher is low, while Shimada may tickle Akari's motherly tendencies and habits and can support her dreams financially, but can't deal well with stress.
Also, there might be another character getting into the picture later.
And in the end, it depends on how Akari feels about committed relationships.