In chapter 99, it reveals a bit of Yuuki's past. Makoto finds Yuuki kind and strong unlike other people who finds Yuuki as a monster. He wasnt afraid of Yuuki and became friends with him, calling him, 'Yu'.
He seems like a very important person to Yuuki, since Yuuki is willingly to even attack the innocent just for him.
He is always seen in a state of coma, but in chapter 105, he seemed to also have felt Yuuki's sonic wave. He was able to move his finger, even sending Yuuki a morse code. He was in a coma state as he was badly injured while protecting Yuuki from falling debris.