It's Andan colors, although the hue is a little off, which makes him laugh a little, but warm and soft when he puts it on. He wonders if it was a deliberate choice, given all his turtlenecks, to help him hide his scars. Either way -

Gonou gets a note back in neat ink calligraphy, tucked under his door.

Thank you. It's beautiful, and I love it.