Chapter six of Mimi no Kaidan.
Mimi and Naoto have a vicious fight over the existence of ghosts. Naoto, despite everything he's seen is in denial and refuses to believe ghosts exist. Mimi's friend Misa says that she believes in ghosts, and something weird is happening to her even now. She takes Mimi over to a half-demolished house that was owned by her family. The workmen stopped halfway through when they discovered a mysterious room under the cellar. It's a proper room with a tatami floor, but has no entrance or exit (save for the hole the workmen dug) and a strange red circle on the wall. Misa explains that her uncle wanted the house demolished against her grandparents' will but, when her grandfather saw the wall and circle, he insisted the room must be sacred. He wouldn't leave, and disappeared shortly afterwards, with no trace of him ever found. Misa's grandmother then disappeared as well. Her uncle had told her that the circle on the wall was getting bigger and darker; but then he became the third to vanish. In the present, Misa agrees that the circle is changing. She believes it is some sort of portal to the afterlife.
A few days later, Misa says she's found something new; and invites Mimi over to the house. There she pushes Mimi into the room and takes her phone before sealing off the entrance. She says that her family really did disappear, and now she wants Mimi to disappear too. Misa goes off in search of Naoto and tells him that she has feelings for him, but they can be together now because Mimi wanted to break up with him. However, he's distracted by the sound of Mimi's voice.
Inside the room, the circle gets bigger and bigger and is about to swallow Mimi when Naoto breaks in and rescues her. He had heard her voice and followed it there. They leave Misa alone in the house, and shortly afterwards she disappears. The house is eventually demolished altogether and everything, including the underground room, is buried.
The story is followed by a short epilogue in which Junji Ito has drawn himself, talking about the character of Mimi and his favorite of the stories.