[Naganain] In the school trip bus - Water bottle and band-aid

A school trip grinds to a halt in a hopeless traffic jam, and poor Nakasato is squirming in her seat as her bladder reaches its absolute limit while the bus refuses to move. The boy next to her, determined to help someone in need, ransacks his bag and offers up his water bottle as a makeshift container—leading to an intensely intimate moment of desperation, her shorts pulled down as she fills it while he burns crimson and tries not to see what he cannot help but hear. A bonus epilogue reveals the aftermath he never expected: unable to stop picturing what that now-washed bottle once held, he spirals into flustered denial over thoughts he knows he shouldn't be having.