Talking about Yokohama --- it is one of Japan's major ports along Kobe, Osaka, Nagoya, Hakata, Tokyo and Chiba.
Yokohama Chinatown is the largest Chinatown not only in Japan but also in Asia (larger than Chinatowns in both Kobe and Nagasaki) and it is one of the largest in the world -- over 200 restuarants included.
For a visit to Chinatown, just try to get off at Ishikawa-cho since it's a short walk from there. No way to get lost since, on the station, there're signage painted on wall for "China Town". After walking for few minutes, there's white entrance.