Haruka, feeling both affectionate and slightly annoyed that her older brother is always asleep, decides to straddle him and wake him up. In that instant, her brother's cock involuntarily erects and slips into Haruka's pussy. Not yet fully understanding the meaning of sex, Haruka feels pleasure mixed with confusion, her body instinctively responding. When he then cums inside her, Haruka's surprised reaction is incredibly cute and deeply captivating.