Also titled "Coffin". Chapter three of Souichi's Diary of Curses.
When Souichi's grandfather dies suddenly, Michina and Yuusuke (who first appeared in Souichi's Diary of Delights) come to stay for the funeral. Michina is surprised to see Souichi cry, and thinks that maybe he has feelings just like any other kid.
Kouichi tells his cousins that a week previously, their grandfather seemed to have had some premonition of his own death. They found him out in the back yard building a coffin for himself, despite Kouichi and Sayuri's warnings that to do so would be extremely unlucky. Souichi was overjoyed and asked Grandpa to make him a coffin to use as a bed. Grandpa made him a Japanese-style coffin, which Souichi rejected because he wanted one with six sides like Dracula's; but Grandpa, who didn't know what western coffins look like, built a hexagonal-shaped one. Souichi didn't like it and shouted at Grandpa, who died that night. Later, as the family goes to put Grandpa into his coffin, they find Souichi chanting mysterious words over the coffin. Souichi says it's a curse to bring Grandpa back to life, because he has "unfinished business" in this world - building the coffin that Souichi wanted.
Michina has to get up in the night and go to the bathroom. She is annoyed to observe that everyone who was supposed to be keeping vigil over the altar (a traditional funeral rite in Japan) has fallen asleep. When she goes down to the basement to reach the bathroom, she hears the noise of nails being hammered. She thinks it's Souichi but is horrified to see her grandfather, returned as a zombie, building the western-style coffin that Souichi wanted. She screams and runs up the stairs, awakening her father and uncles who were supposed to be keeping watch.
They follow her to the basement and are surprised to see the coffin, which hadn't been there before. The lid of the coffin opens but it's just Souichi, who says that Grandpa had built it before he died for Souichi to sleep in. He says Michina must have had a nightmare and it's impossible for the dead to return. Sure enough, the body is still in its coffin, but Michina wonders if the curse really worked and that's why everyone fell asleep when they should have been upholding the vigil.
At Grandpa's funeral, everyone is shocked when after he goes into the crematorium, no ash comes out, not even bone ash. The mourners also get the strange feeling that someone is following them. Michina sees Grandpa ahead of her in the crowd and, when the mourners look, they see him among them. They soon realize that he is a zombie; and run screaming.
Grandpa returns to the Tsujii house, where he continues to make coffins, all of which Souichi rejects. Grandpa will be unable to rest until he completes a coffin that Souichi likes. The coffins continue to pile up.