Lan Wangji smiled, and even grins, brighten up that he agrees on an idea to spend a day with him.

"Yes, I would like that." And this reminds Lan Wangji to tell him of his day. "I tried washing our robes at the laundromat..." He trails off because the laundromat was a nightmare by itself. "Since it's the only ones we have since we got here, but the bloodstains are hard to wash off. So I found some clothes from the town's thrift shop. I put some clothes I found in a closet, so I hope they fit you."

Which explains why Lan Wangji wears a t-shirt and a pair of faded jeans.