How to get to Leimen from Haneda Airport in Japan?

You mean the Ramen Hotel suggested a route for you without changing trains:

After leaving the station, walk to the terminal of Haneda Airport's domestic line, take the Gyeonggi Airport Line (Express Tejingchenggaosha), continue to take the same train on the Gyeonggi Line after 2 stops, continue to take the same train on the Asakusa Line after 2 stops, and get off at Asakusa Station after 1 1. After leaving the station, walk 350 meters along the zebra crossing and sidewalk to the hotel.

After coming out of Asakusa Station, turn left and go straight to the intersection, turn right along the zebra crossing, and then turn right.

Then walk north along the sidewalk, cross the zebra crossing at Leimen, turn left, then turn right and then turn left to the hotel.