Haruna Aihara and her son share a calm, affectionate daily relationship. However, the son harbors a secret desire to see his mother going to the bathroom. Unable to suppress his urge any longer, he slips a suspicious diuretic he obtained online into her drink, deliberately inducing the need to urinate. As a result, Haruna is forced into an unexpected situation—urinating outdoors. This incident becomes a moment that profoundly shakes the bond between mother and son.