His head snaps around like a whip the moment he hears that cough, because it's never mattered how many times Souji tells him to piss off, to stop being a mother hen, that he's fine and it's under control and he can manage perfectly well without help or concern or pity -

At the end of the day, one can't expect Hijikata not to worry about family. Especially when that's all the family he has left.

He's by Souji's side in an instant, faster than he can even collect his words and ask. He knows that he should be trying to get the message somewhere, put down whatever suspicions they have and hope that maybe it'll give them one more thing to think about when this nightmare starts all over again, but -

Souji.

He's lost enough people by not being there. It doesn't matter if a sword can't save Souji, if illness is the kind of enemy he doesn't know how to fight and can't fight in someone else's name.

He can't not be there.