Souichi's Diary of Delights is volume five in the Horror World of Junji Ito series. It was originally published in 1997. To date, none of the works in this volume have been officially translated into English. Fans have unofficially completed the English translation.
The stories in this collection focus on Tsujii Souichi, a young boy who is obsessed with curses and the occult, much to the annoyance of his typical Japanese family. Souichi tends to not only make trouble for other people with his strange and mischievous behavior, but he also gets himself into hot water as well.
A troublemaking 5th grader. He was raised primarily by his grandmother, and is the black sheep of his family. Due to a lack of iron in his blood, he sucks on nails and holds them in his mouth. He also has the ability to shoot them out of his mouth like darts.
Souichi's older brother is 15 years old. He is kind and level-headed. He tries to take care of Souichi, but is frustrated with his strange actions like the rest of his family.
Elder sister to Souichi, and younger to Kouichi. She is in the seventh grade.
Michina and Yuusuke Hirose
Souichi's second cousins that come to visit Souichi's family.
Chapter 1: Fun Summer Vacation
Yuusuke and Michina visit their extended family in the countryside. While sharing shaved ice with the rest of their family, Yuusuke asks about Souichii's whereabouts. Kouichi, Souichi's brother, says that Souichi is very shy. Later Michina and Yuusuke go to greet Souichi and hear talking through the door. They see the boy apparently talking to some dolls. When he notices them, he spits a nail from his mouth to scare them off. Kouichi says that Souichi is anemic and sucks on nails to compensate for his low iron levels in his blood. When he finds out that Souichi spit a nail at them, Kouichi scolds him.
Souichi hangs around his cousins and siblings but never participates in whatever they are doing. He is invited to play cards, but says that it's an idiotic thing to do. But he is frustrated that Michina will not look him in the eyes.
In the middle of the night Michina's stomach starts to hurt and she heads to the bathroom, but stumbles upon Souichi nailing a doll to a post in the storage room, shouting "Michina, suffer!" and laughing. She tries to tell Yuusuke but he doesn't believe her. The next day she chooses to stay in bed instead of going out with them, and is visited by Souichi holding another doll. She ignores him, so he plunges it into a fishtank. Shortly after Souichi's sister, Sayuri barges in, and Michina finds out that Yuusuke nearly drowned at the pool. He says that he was walking along the edge of the pool and was pushed in, but there was no one there to push him.
Later that night Michina tries again to tell Yuusuke that it was Souichi's doing, but he seems to ignore her. Souichi creeps on their room and says that because he doesn't have enough blood, he has to sneak into the streets and get it from other people. He bares "fangs" of nails and lunges at Michina who slaps him away, which causes the nails to pierce through the side of his cheek.
Michina and Yuusuke finally depart from their family vacation. Souichi even shows up to see them off, daring them to return.
Chapter 2: Fun Winter Vacation
Yumiko Fukaya is visiting Souichi's town, but gets lost on her way from the station. She discovers one of Souichi's voodoo dolls nailed to a tree and, in frustration, whacks a nail into it. Souichi appears and taunts her, causing her to run after him and fall into one of his traps. He triumphantly says that she will freeze to death. Kouichi rescues her and takes her back to the Tsujii house but notices that she has mysterious wounds on her neck that look like nail punctures. Yumiko mistakes him for "Hirose".
Yumiko awakes and talks to the Tsujii family but is interrupted by Souichi demanding shaved ice. She is horrified when she sees that he is the boy who hurt her. Souichi gets annoyed that his mother used the ice in a water pillow for Yumiko, so he starts eating snow instead. Kouichi asks her why she was travelling alone and why she called him an unfamiliar name, but Yumiko denies it.
Souichi confronts Yumiko and says he knows that Hirose rejected her romantically. He is eating snow with red syrup and Yumiko wonders if it's her blood. Souichi offers to curse Hirose and also says that it will snow. Sure enough, the next day there is an enormous snowstorm. Michina and Yuusuke are supposed to be coming to stay, but then Yumiko hears a news announcement that Yuusuke Hirose has been critically injured in an accident during the snowstorm. Souichi is disappointed that his curse failed and Yuusuke isn't actually dead.
Yumiko's fever returns. Souichi taunts her with the knowledge that Yuusuke was the guy she liked; and says he took more blood while she was sleeping. He explains that Yuusuke is his cousin and thus, looks like Kouichi. Yumiko blames herself for Yuusuke's accident and tries to go outside, but collapses in the snow. Kouichi rescues her and takes her back to the guest room where they find Souichi writhing on the floor, having a stomachache from eating the snow. Yumiko tastes the syrup he had with him and finds out it's strawberry. She recovers and leaves when the snow melts, but doesn't know what Souichi really did to her neck.
Chapter 3: Souichi's Diary of Delights
In this story, it's a year on from "Fun Summer Vacation" and Michina and Yuusuke have come to stay with the Tsujii family. They haven't seen Souichi for a year because Yuusuke was injured during the winter break and couldn't visit. Souichi is angry at Michina for the incident the previous summer when she injured his face with his own nails by slapping him; and puts a curse on her. She reads his diary and discovers that he is planning revenge on her as well as that he caused Yuusuke's accident in the winter. Souichi's curse causes tentacles to grow from Michina's face at the spots where the nails wounded him; but she confronts him with the diary and her knowledge of his crush on a classmate. Souichi ultimately lifts the curse.
Chapter 4: Souichi's Home Tutor
Chapter 5: Mannequin Teachers
Chapter 6: Souichi's Birthday
It is Michina's birthday and the family celebrates with her, but are interrupted when Souichi pops up from the attic and spits nails onto the cake. Kouichi explains that it's Souichi's birthday too. The family has to move rooms because of all the noise Souichi is making upstairs. Souichi is delighted when Kouichi trips and drops Michina's cake; but gets annoyed that the cake wasn't destroyed. As everyone settles down to enjoy the cake, Michina muses that Souichi doesn't look like anyone in the family. However, Kouichi produces a picture of his late grandmother, who looks exactly like Souichi. He tells the story of her and Souichi.
Granny was known for being strange like Souichi, and for telling fortunes which didn't come true. When Mrs. Tsujii was pregnant with Souichi, Granny predicted that the baby would be twins. Even when Souichi was born as a single baby, she still insisted that he had a twin beside him. She named the baby Souichi, and his "twin" Souji, and would play with them even though Souji wasn't real. As Souichi grew up, he began to look like Granny and to carry nails in his mouth like she carried a toothpick. One year, Granny mysteriously disappeared and was never seen again. The family believes that she had developed dementia and couldn't find her way home. There was a reported sighting of her with a child, but the family is convinced it couldn't have been her.
When Michina goes to get a blanket from the closet for Grandpa, she finds Souichi hiding in there. He tells her the blankets are in the other closet but, when she opens it, she sees Granny. She runs for the rest of the family, Granny has disappeared. They think it must have been an illusion. Later, Souichi jumps out at Michina when she is in the garden with Kouichi. He warns that Granny and Souji come to see him every year on his birthday and that they will do something bad to Michina if she sees them again.
That night, Michina is woken by the sound of laughing. She follows the noise and hears Souichi laughing, along with Granny's voice saying that she and "Souji" will find Michina and teach her a lesson. Granny and Souji appear and violently attack Michina. She screams for Yuusuke to wake up but Granny warns her that he won't. Meanwhile, Souichi goes into his room and finds that Michina wrote him a kind note and saved him the slice of cake with the nails on it. The ghosts suddenly disappear and Michina doesn't know why. Souichi gobbles down the cake even though he says he doesn't like it.