Shiki and Ichijo maintain a close friendship partly because of the fact that they are roommates (though Ichijo 'dominates' most of the room with his manga, as explained in the Official Vampire Knight Fanbook) and also because both of their families are on the side of the Vampire Council. It is said in the Official Vampire Knight Fanbook that Shiki has developed an attachment to Ichijo which Ichijo defines as "cute". The two are often seen caring greatly for one another such as when Shiki's body was taken over by Rido and when Ichijo is kidnapped by Sara. In the manga, Takuma states that Shiki is an "Ichijo" an endearing sentiment.
When Takuma was cut during his birthday party, he let Shiki lick the blood off the wound, signifying a close bond. Takuma also noted that Shiki seemed rather attached to him. When Rido (possessing Shiki's body) met with his nephew for the first time in ten years and Kaname attacked him, Takuma shielded Rido, not wanting to let Shiki's body be harmed in the conflict between the two Kurans. Takuma also stays by Shiki's side during Rido's possession of Senri's body making sure that Shiki is not harmed. Ichijo carries Shiki back to their room after Rido leaves his body. Senri often leaned against Takuma while he was reading his manga.