Karyuudo Tsukishima

Karyuudo Tsukishima is the Tenth diary owner. A lover of dogs, Tsukishima runs a kennel home and breeds dogs, however, he has also trained them to attack and kill people. His diary is the "Breeder Diary". He is the father of Hinata Hino.

Personality
Tsukishima is a wealthy gentleman who runs Sakurami City's dog home, treating each of his dogs like a beloved family member. He is shown preparing for them expensive meals including wine, and even has them sitting at a long dining table, although it appears they are not trained in table manners. Tsukishima appears to care little for humans, including himself, eating noodle meals. Because of his detached attitude, Tsukishima has isolated himself from his family. He is shown to have a wife, but where she is during the events of the manga are unknown. His daughter Hinata loves her him and wishes to earn his attention and love, having often been neglected by Tsukishima, even as a young child. Tsukishima is well aware of Hinata's need for approval, considering her to be very naive and "easier to fool than a dog".

As a diary owner, Tsukishima trained his dogs to be murderous attack dogs, giving them metal mouthpieces to enhance their bites and physical attacks. He also owns a large computer mainframe which he uses during his planned attack against Yukiteru Amano and his friends. His diary is the "Breeder Diary", which he uses to predict the movements of his dogs and those of his targets. However, controlling several units of dogs makes it difficult to properly use.

Despite his icy exterior, Tsukishima appears to show some remorse for not being a proper father to Hinata, asking her not to become a bad person like he did.

The Gamble
Karyuudo Tsukishima debuts with the other diary owners at Deus Ex Machina's first meeting of the survival game. Like the others, he decides to make the First owner, Yukiteru Amano, his target. By late May and early June, four diary owners had been killed, leaving Tsukishima quite fearful for his life. He begins to notice Aru Akise lurking about outside and informs Hinata of his presence, guessing he is a fellow diary owner. Tsukishima comes up with an idea to give Hinata power over his diary in order to expose Akise as a diary owner, as well as make his move against Yuki. During the second meeting with Deus, Tsukishima requested to give his diary to a third party, much to Deus' surprise. Keigo Kurusu, the Fourth diary owner, informs Yukiteru of this event, revealing Deus believed it was at first an excuse to get out of the game but then allowed Tsukishima's request. Tsukishima loans Hinata his diary and his attack dogs, promising Hinata that if he became God, he would go back in time and make up for neglecting her.

Having trained his dogs to attack people, Tsukishima stages a number of serial killer-like murders, creating a similar public scare like that of the Third diary owner Takao Hiyama. The dogs work on their victims was at best horrible, acting devouring parts of their victims' bodies and leaving the remains for the police to find. When Yuki starts his new term at Umesato Elementary School, Tsukishima had lent his diary to Hinata, giving her the opportunity to gain his love and approval. Upon meeting Yuki, Hinata suggests investigating the sites where her father's dogs killed people. Yuki agrees, accompanying Hinata, Mao Nonosaka, Ouji Kosaka and the Second owner Yuno Gasai to the park where they find one of the crime scenes. Hinata runs off ahead and fakes her death, using a fake arm to make it look like she has been torn apart by her attack dogs, on loan from her father.

Akise arrives, escorting Yuki, Yuno, Mao and Kosaka to a nearby building where they manage to fend off the dogs following the instructions on Yuki's diary. Afterwards, Mao reveals herself to be in league with Hinata, taking Yuki at knifepoint. Hinata enters and takes Yuki's phone, accusing Akise of being a diary owner himself. However, Akise uses a coin toss game to outwit Hinata who tries to use Yuki's diary to predict the outcome of each coin toss. However, Akise deceives Hinata and she is forced to surrender Yuki. Akise fools Yuki into believing he has a Future Diary in order to ensure victory, but Yuno attacks him and reveals the truth. Nevertheless, Akise performs a final coin toss after conspiring with Yuno to again fool her by tricking Yuki into believing he failed at the coin toss.

Yuno attacks Hinata to get Yuki's diary back, but Mao takes a blow for Hinata and is stabbed. Yuki, Yuno, Akise and Kosaka take the opportunity to flee. The enraged Hinata orders all of the dogs to chase them, and the goes outside with the wounded Mao where she regrets her actions, believing Tsukishima will never approve of her. Yuki returns with the intention to save Hinata after she promised that they could all leave as friends if she failed the coin toss game. Yuno charges in first, taking Hinata at knifepoint and threatening to kill her unless she surrender the Breeder Diary. Yuki manages to calm Yuno down by declaring to his friends that she is his girlfriend, allowing Hinata to be spared.



Hinata laments for failing her father, only for Tsukishima to speak up through a radio device on a dog, actually listening to the events the whole time. Tsukishima apologises to Hinata for mistaking Akise for a diary, but reveals his role in the game is over. Hinata asks about his promise, but Tsukishima apologises again and reveals it was a lie; in the anime, he openly laughs at Hinata's naivety and his own promise. Tsukishima criticises Hinata for her naivety, but tells her not to become a bad person like he became. Clutching a family photo of himself, his wife and a young Hinata, Tsukishima informs Yuki to beware of the diary owners who act nice, believing they are deceptive.

Kurusu suddenly appears behind him, having tracked him down using his own diary. Tsukishima identifies Kurusu as one of the "nice people", and is shot in the back of the head by Kurusu, his death heard by Yuki and Hinata. Kurusu frames Yuki and Yuno for killing Tsukishima, to cover up his own actions in his plan to become God to save his terminally ill son. However, Masumi Nishijima eventually clears Yuki and Yuno of the charges when Minene Uryu reveals Kurusu's alliance with her.

The Third World
Tsukishima appears in the third parallel world created when Yuno, Muru Muru, Yuki and Minene perform a time leap two years into the past. Tsukishima's dogs are disturbed by the explosions occuring at Sakurami Elementary School caused by the four time travellers, Tsukishima heading outside to check on his pets. However, he is surprised to find Hinata calming down the dogs. Hinata admits she has gained an attachment to the dogs, leading to a better relationship between Tsukishima and Hinata, altering the future.

In the last chapter, Tsukishima, his wife, and Hinata are seen among the supporting characters on the streets of Sakurami City, living a better life together.

Trivia

 * Karyuudo is not actually named until after he is killed by Kurusu.
 * His name is a nod to the Roman moon goddess Diana, his name containing the kanji for "moon" (月) and "hunting" (狩).
 * In the manga, Karyuudo's dogs wear large metal mouthpieces whilst in the anime, their teeth are shown to be wearing metal, serrated braces-like devices.