Kouchisei was seated in the back, and from there he was glancing occasionally from Ishino to the guard. He had found the strength to look at people directly, but still believed it rude so he switched to staring at the bulletproof divide.
He preferred being able to observe Ishino's movements and have time to analyse her words. The thought of doing the talking caused him to cusp his hands in his lap and say nothing.
If Ishino was an angel, it didn't strike him as productive to be in custody.