Umi, the younger sister, gets caught up in a threesome with her older brother and his friend. Although it started on a whim, she was originally interested in sex and had experienced physical relations with her older brother several times in the past. However, it seems even she didn't expect to suddenly have sex with three people today. When she actually sees two big dicks, her pervert switch is triggered, and she can't help but grip them with her mouth and shaved pussy, and in the end, she gets creampied.