IENE-433 — My Sister Was Dumped By Her Boyfriend, So She Canceled On Her Hot Springs Trip, So I Got To Take Her Place, And To My Surprise, We Ended Up Sharing A Room In A Mixed-Grade Open-Air Bath!

After her boyfriend canceled on her, her older sister brought her younger brother along on a hot spring trip because she didn't want to waste time. Since she was supposed to go with her boyfriend, they naturally shared a room and bathed together. He got an erection when he saw his older sister's big breasts, which he didn't usually pay attention to! As he tried to hide it, his older sister came closer, shaking her big breasts. He thought he'd get in trouble if she found out, but his older sister couldn't help but stare at his erect penis...