Big sis Maria is watching over you... but this time, she spends summer days with a boy her age who recently moved in to the Miyori Apartment complex. Having lived a life of domestic violence, the boy finds solace in Maria as they become more than friends after just a few months of being together. But something strange happens when Maria starts becoming distant... as if something is going to happen on the day of the boy's birthday. This is the fourth installment of Yanyo's "Big Sis Loves Nobody Else But You" Series where the truth behind the secret of what Maria is is revealed!