Yes. English. LOL.

Depends on which public high school you go to. The high schools I went to require you to study 3 years of foreign languages. The foreign languages also differ depending on which places you go to. For example, in one of my high schools, the foreign languages that were offered were French and Spanish. In my other high school, they had more options such as Italian, Spanish, and Chinese Mandarin.

This is purely the view of an American outsider. I don't think that the Americans value learning a different langauge to English. I know that Spanish is an important second language in the US but the American education system seems not to push things like geography or foreign language studies. Apologies to the Americans present, but perhaps they would like to answer Shinji as well.

English speaking Canadians must study French for 5-7 years. It generally becomes option after the first year of high school.

as Japanese lost WW2 it caused the situation that Americans came to Japan and brought English as for schools -- they can choose the language to learn Spanish, French and Chinese are most popular now