Dimitry is a former vampire, and the main character of the Special Halloween 2011 Episode. He later appears reincarnated as a human in Episode 19 at the mall. In late June 2014, he later replaced Boris as the character who welcomes you in the introduction episode along with ChiNoMimi.
Originally, you first meet Dimitry in the special Halloween 2011 Episode, after finding him standing in front of what seems to be a grave. As of recent, he makes his first appearance in Episode 0, greeting the player in place of Boris. He is the the first boy whose lov'o'meter is affected by your response.
Your Candy mentions that he seems sad as he stands over the grave of his ex-lover, Mary Magdalene. Dimitry explains he takes care of Mary's tomb to treasure her memory. He then goes into detail about why he became a vampire, why he wanted to turn Mary into a vampire and how he failed to save her from her illness. Due to this failure, he has been trapped living that lonely life.
During his appearance in Episode 19, he mentions that he came to the mall with his girlfriend.
Dimitry has long ash-brown hair that reaches down to his waist and piercing red eyes. His original eye color is brown. He dresses in a Victorian fashion, supported by the fact his lover died in 1860, similar to how Lysander dresses (only Dimitry's is authentic), and as your Candy has stated before he also seems to look "sad" or "lonely."
In his human form, he can be seen wearing a black coat with a purple undershirt, and black pants. The clothes are a changed and recolored version of his old ones.
Dimitry is supposedly the second easiest guy in the game to speak to, however this is down to subjective opinion (the first being Ken which is evidently proven) he also is a sweet, caring man cursed by failing to save Mary's life. He's lonely, but he is unwilling to let go of the memory of Mary.
Despite not willing to let go of Mary's memory, he comments on how you look like her, act like her and even gives you an outfit composed of a dress and accessories, which Mary wore.
Dimitry also drinks your blood, if you allow him to, as he is getting weaker as the years go by, this shows he does not want to die, for reasons unknown. Dimitry also requests you stay with him (Black says "goodbye" so maybe he sends you home) why he wishes to stay is unknown. Dimitry subconsciously may have wanted Candy to stay, because it was like having "Mary" again, so he is a realist who knows she has died, yet he's longing for either a friendship or a romantic relationship.
Dimitry is shown to be rather gentlemanly due to how he approaches the Candy about her blood, including the times he tried to avoid taking her blood. Since Dimitry owned the castle, it is possible he was a prince/king or at least someone of high wealth, shown through his mannerisms. Dimitry is a man of few words and few facial expressions however he does smile now and then while spending time with your Candy.