This man loves and values his dogs more than himself; as shown when he cooked them steak and give them thirty-year-old wine for dinner, while he himself was content with eating cup ramen.
He is the owner of the Tenth diary, The Breeder's Diary, which allows him to check on the status of his beloved dogs and control them in squads via voice commands. The dogs can be used to chase and kill people. The diary's weakness seems to be issuing the order of chasing multiple targets, which would require greater concentration in herding the dogs and would also leave the user vulnerable to attack as the holder would be alone.

As he was concerned about a stalker and potential diary user, the Tenth literally placed his future in the hands of his daughter, Hinata Hino, who recognized the stalker as a classmate of hers, Akise. Armed with the diary and her father's dogs, Hinata set an elaborate trap to capture Akise, using Yukiteru as bait. The Tenth was killed by Keigo.

He is named after Diana —the Roman goddess of hunting.

(Source: Wikipedia)