I know right? Like, chapter 2 of the WN has a bunch of parts describing Sendai's increasing frustration and anger at Miyagi not accepting the leftover change. You can kinda sorta sense it on page 15, but not to the extent as described in the WN below:
...And besides, the fact that she thought I was the kind of person who would just be like, “Oh, sure, thanks!”, in response to keeping the change really got on my nerves.
「Ahh, whatever. Let’s just say I borrowed the change as well. I’ll just give it all back to you tomorrow.」
To be honest, I was really starting to get angry, but I held myself back.
If rumors of me yelling at someone else started circulating around at school, it’d only serve to ruin my image.
But we'll see either way, I have faith! I feel like they're almost certainly aware of such a problem. Anyway, maybe they could use more thought boxes for the internal monologues or something lmao
The manga seems much colder than the LN without the blow-by-blow recount of their internal states.
To be honest, I like this coldness. I like it when things are, but are left unsaid.