Wagamama Chie-Chan summary:

Just before Saho Hanawa was about to matriculate into Seiran Middle School (her mother's alma mater), she meets a ghost girl, Chie, who's wearing the Seiran school uniform and standing in the rain. Saho assents when Chie asks to go to Saho's house, and they spend time talking and arguing with each other. Saho parents hear her talking to Chie and assume she must be talking on a cell phone - until they catch her talking to empty space in her room. Saho is forced to confess that she can see a ghost girl named Chie, which shocks her parents. They then reveal that Chie is the name of the stillborn baby that they had before Saho - Saho's dead older sister.