Normally serious and sweet, the younger sister has recently been growing increasingly interested in sex. Drawn by moans coming from the next room, she quietly peeks in and sees someone masturbating intensely. Though her movements are awkward as she touches her pussy, her excitement gradually builds. She sniffs the sleeping sister's sweet scent, then slowly removes her underwear. Trying hard not to make any noise, she suppresses her sounds, but faint breaths and sticky wet noises can still be heard. She knows she shouldn't be doing this, yet she just can't resist...