Everyone letting out a sigh of relief that this side story ended ain't ready for the plot of the next one
is the main conflict like.... kana obv is possessive over naho (given that he gets mad when his friends try to take the cranes) and being popular he tried to deflect attention off naho by saying he's "average".
the upperclassmen seem rly curious about naho so I feel like there's nothing super insidious happening, it's more there's a lot of interest around naho that kana does not want (his reaction to naho having friends).
Like obv he's a bit of a dick for prioritizing his possessiveness over nahos actual feelings and self esteem (╯°Д °)╯╧╧
I thought the letter was gonna be about him going back to war or some conflict I was so nervous for this chapter bc I feel like we're on the final arc and was not prepared for more drama