Karyuudo's attack dogs are the dogs from his kennel that he has trained to be vicious killers. He used them in the Survival Game, to attack the other competitors. He has outfitted them with metal mouthpieces to enhance their bites and physical attacks.
The attack dogs were once dogs at Karyuudo's, but he trained them to be killers. He also outfitted them with metal mouthpieces to enhance their bites and physical attacks.
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. Each and every dog apparently has a tracking device on them, so that Karyuudo can monitor them on his computer. He also has at least one dog fitted with a speaker collar and listening device to help monitor the situation.
The dogs are controlled by the The Breeder Diary witch allows the Tsukishimas to control the dogs like an army. The dogs are apparently very well trained, but it is unclear if this is just the effects of the dairy. It is implied the user can see what the dogs see through the phone or at least relay information has Hinata Hino some how new the dogs had lost the others despite not being in visual range. Though the more dogs there are the harder it is for Tsukishimas and Hinata to keep track thaw Tsukishimas could apparently negat this by using his computer to help keep track of the dogs and Hino could simply her commands by just giving a command to one team of dogs and telling all the other tams to fallow.
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, who had actually been listening in the whole time. Tsukishima apologises to Hinata for mistaking Akise for a diary owner, 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 criticizes 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, but can also be deceptive.