There are FOUR international schools in Yokohama city, offering K12 education. In addition to this, there are TWO international schools that offer education in non-English languages.
If you want to explore more schools, you can check out International schools in Tokyo. There are many people working in Yokohama and living in Tokyo for the sake of school and other reasons like proximity to their community. And Vice versa.
Click the below school name(s) to get the details of the international school.
Saint Maur International School
Naka ku, Yokohama
Yokohama International School
Naka ku, Yokohama
Horizon Japan International School
Tsurumi ku, Yokohama
Indian International School
Midori ku, Yokohama
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Deutsche Schule Tokyo Yokohama (German School)
2-4-1, Chigasaki-Minami, Tsuzuki-ku, Yokohama-City, Kanagawa-Pref.
http://www.dsty.ac.jp
Yokohama Overseas Chinese School (Taiwan based Chinese school)
142, Yamashita-cho, Naka-ku, Yokohama-City, Kanagawa-Pref.
http://www.yocs.jp/