That Blue Summer Vol. 4 (Kodansha, 2020)

With Rio's Tokyo pals mingling with Ginzo's, Ueko has gone from quaint village to full-blown summer camp… and what summer camp is complete without a test of courage? Rio's going to need THAT in spades, after being randomly paired with Kanno of all people! Meanwhile, Ginzo can't stop glaring at the guy, and that's only making her MORE confused!