Tanjiro was at a train station, waiting for his group. Though it wasn't the Mugen Train, it was still triggering his PTSD.

He didn't really want to go on a train again, but he had to. If he didn't, he's job in the Demon Slayer Corps wouldn't go so well.

He was leaning against a wall, it was raining out. The roof over the station kept everyone there from getting wet.