Souji took that hum as a sign to continue what he was doing, letting his fingers map and learn, easing him into new territory.

Much more tentatively, his other hand moved to trace the more complex scars on Hijikata's other shoulder, more of a mystery to him, from a time before he'd known Hijikata. But he was careful, knowing it was a touchy subject, not wanting to ruin things by daring too much.