I Fell in Love With My Cool FWB but She Brought Her Big Breasted Sister Over

Event-collecting RPG 30+ Basic CGs 1 HAPPY END --- Kosuke and Sana met at university, exchanged their first experiences, and even became Friends with Benefits. Neither of them liked romance, so their relationship was simply to satisfy their sexual desires. But Sana, who was usually expressionless and cool during sex, began to have increasingly cute reactions. Kosuke fell in love with the changed Sana. After that, at Sana's suggestion to split the rent, they started to live in a new apartment together. However, Sana was not his only roommate; her busty hostess sister, Aira, was also there. What's more, whenever Kosuke and Sana had sex, Aira would always join in, pressing her pussy against him and making him lick. Unable to see Sana's cute reactions, Kosuke began to question Aira's constant interference. The truth is always the same. There is always only one truth. "Could it be that her sister likes me...?" That's impossible... No, maybe it's not impossible!? So, a harem romantic comedy begins, and everyone will become happy.