Kazuki Karaiya (仮頼谷 一樹 Karaiya Kazuki) is the main antagonist of Crazy Diamond's Demonic Heartbreak, a spinoff manga of JoJo's Bizarre Adventure. He is a police officer and implied to be a Stand user with a currently unknown Stand. He is also capable of manipulating Petsounds's unnamed Stand and Tohth.
Karaiya is tall with an androgynous appearance. He has light-colored hair styled in a bob cut, a mole below his right eye, and flat eyebrows. He wears a typical Japanese police officer uniform in the springtime consisting of a hat with an emblem on the front alongside a coat with a white dress shirt and a dark tie underneath.
Karaiya normally appears calm and serious, but is secretly deranged, sadistic, and an elitist. Despite being a police officer, he is fine with Petsounds attacking innocent civilians, including Josuke Higashikata, the grandson of Karaiya's coworker, Ryohei. Karaiya allows criminals like Koji Kiyohara to roam free if it means they can be of assistance to his plans. His calm demeanor can quickly change to reveal his true nature when he is angry.
Karaiya is motivated by his grandfather's desire for them to stand at the top of the world together. He inherited his grandfather's ideology which the latter learned from Kars, where the winner should focus on being the one who comes out on top. Before being granted any power by his grandfather, Karaiya felt lost. However, he now feels like he could do anything, especially with Petsounds by his side. He has a superiority complex, perceiving other people around him as ignorant imbeciles. Karaiya initially acts friendly when speaking with Boingo, but it is merely an act that he puts on.
- Main article: Petsounds's Stand
As Petsounds's owner, he is capable of fully wielding its Stand for his own gain. Petsounds's Stand is capable of recording events from the past in punched cards and inserting them into someone's body. The victim's body is then forced to reenact the event, essentially parroting what happened.
- Main article: Tohth
Tohth is a comic-book-like Stand whose whimsical story periodically updates itself to predict the close future with 100% accuracy. After incapacitating Ryoko and Boingo, Karaiya takes the book for himself.
When Karaiya was young, his grandfather advised him not to open his heart to humans because of how shallow they are. Before World War II, his grandfather was at St. Moritz, Switzerland for an intelligence operation, where he experienced something that transcended all of creation. He never shared the truth with Karaiya's father, but decided to tell Karaiya since he felt that both of them were similar. His grandfather passed on the ideology he learned from Kars to Karaiya and later shared a part of his Vampire essence to Karaiya when he became an adult.
At the Budogaoka Police Station, Karaiya takes interest when Boingo mentions that he lost a manga. Ryohei asks Karaiya to escort Boingo back to his hotel. Before they leave, Karaiya ominously hopes that Ryohei could get a promotion someday for his hard work and passion.
Later, Karaiya has Petsounds use its ability to possess a group of chefs. Watching from an alley, Karaiya witnesses Hol Horse using his Stand to defend himself and is excited to learn that there are other Stand users in Morioh.
Without directly meeting him, Karaiya gives Koji Kiyohara permission to kill whoever he wants in Morioh's subway station, while also having Petsounds attack Josuke and Hol Horse. However, Kiyohara and Petsounds are both defeated by the duo, allowing Ryohei to arrest Kiyohara. While Kiyohara is in his jail cell, he sees a memory of Karaiya sitting beside him in a police car. Karaiya asks him how it felt to lose. When Kiyohara doesn't answer the question but instead asks who Karaiya is, Karaiya screams at him. Petsounds then appears behind Karaiya and activates its Stand ability on Kiyohara, causing him to shriek in his cell.
Karaiya looks at the civilians around him and feels that he is superior to all of them. Recalling his grandfather's words from when he was younger, Karaiya has full faith that he can crush anyone that stands in his way. Karaiya walks up to Boingo, who is taking shelter from the rain, and asks if he needs a hand searching for his book. However, Karaiya actually incapacitates Boingo and carries him with one arm while looking for Tohth. He eventually finds Ryoko Kakyoin and uses Petsounds's Stand to possess her. With Tohth left on the ground, Karaiya picks it up and becomes its new owner. The pages tell him to give Ryoko a gun so that she can shoot Hol Horse. Karaiya is ecstatic that he can now control both the past and the future using Petsounds and Tohth.
- “Since I, Kazuki Karaiya, have come here to speak to you personally: I want you to answer me nice and clearly. Can you do that? Hmmm? Now, what you say next will determine your worth in the world.”
- “Wrong answer!! That’s why you’re nothing but trash!!”
- “I, Kazuki Karaiya, am nothing like these ignorant lowlifes.”
- “The fact that I have the power of Petsounds in my grasp is proof that I, Kazuki Karaiya, deserve to stand at the top.”
- “Anyone who stands in my way will be granted no mercy!”