About My Adopted Sister Being a Rental Girlfriend

Because their parents said that "living together can save some rent," Ye Yan and Lin Xia, nominal siblings, began an unfamiliar cohabitation life. But now that they have become "family", it seems that they should learn to get along like real brothers and sisters. Get to know each other a little bit through trivial daily activities such as eating, going to school, and activities. I thought that such a peaceful and distant life would continue forever. Until Ye Yan accidentally discovered that the willful, lazy and naughty sister at home was secretly acting as someone else's "girlfriend"! And Lin Xia gradually discovered that the always rational, calm, but withdrawn brother seemed to be changing little by little under his influence.