Karyuudo Tsukishima

Owner of the Future Diary: Breeding Diary

Owner of the kennel "Tsukishima Kennel." A pathological dog lover who believes "humans are inferior to dogs," he serves lavish French cuisine to his dogs while eating instant ramen himself. He is divorced from his wife and lives separately from his daughter, Hinata.

His mobile phone, the "Breeding Diary," has the ability to record his future commands to his beloved dogs and their howling reports. He can issue commands to the leader 'Alpha' from his phone to maintain control.

He used his dogs to kill individuals suspected of being Future Diary holders, but he caught the attention of Aru Akise and proposed to Deus that he transfer his Future Diary to a third party. Although the proposal was rejected, he transferred the diary to Hinata, attempting to have her eliminate Aru in his place, but failed. In the end, he was shot to death by Kurusu.

He lied to Hinata, saying he wanted to become a god and rewind time to start over with his family, but as he died, he looked at a family photo and told Hinata, "Don't become a bad person like me," leaving it unclear whether it was truly a lie.

In the third world, he learns that Hinata is getting along well with his dogs, suggesting an improved relationship. In the final episode, he is seen walking with a woman who appears to be his wife and his daughter.

His name is derived from Diana, the Roman goddess of the hunt.