Can you help me find this BL it’s about a guy who has a strong sense of smell. He was ri...

Can you help me find this BL it’s about a guy who has a strong sense of smell. He was riding a train when he get suffocated and then he was helped by a guy he doesn’t know leaving him a scarf. Since then he’s been trying to find the guy who help him and then he mistook one of his sempai for him because that sempai is wearing the uniform of the person who help him. Please help me, I want to read it again but I guess I don’t save it in my collection