My next door neighbor, Shion, has always been unsociable, cold, and scary, so I don't really like her... But our parents get along well, and she's decided to look after me for a week while my parents are away on a trip! Despite her brusque attitude, she dotes on me and is slutty! She watches my AV with me, invites me to the SM club where I work part-time... and then I suddenly realize. My sister is actually into me...? A completely subjective experience of living together with a tsundere busty sister!