[USEFUL INFO] Converting Your Foreign Driver's License in Yokohama (Kanagawa)

Kanagwa Prefecture Police website (in Japanese)
Converting Foreign Driver's License to Japanese License

Details available in 9 languages (English, Korean, Chinese, Spanish, Portuguese, Thai, Vietnamese, Persian and Russian: PDF documents)
https://www.police.pref.kanagawa.jp/eng/e_mes/eng83000.htm#exchanging

People from certain countries (about 25 countries) don't have to take the written and driving tests. If you don't speak Japanese, you need to bring an interpreter. The procedure, cost, what documents to bring are different according to where your foreign license was issued. You can ask the Foreign License Section of the center beforehand (the number is written on the bottom of the documents above).

You have to go to the Kanagawa Prefecture Police Driving License Center in Futamatagawa, Yokohama (15-minute walk from Sotetsu Line Futamatagawa station, or 5 minutes by bus from the station).



This article on Japan Info Swap is helpful, too!
Converting your Foreign Driver's License to to a Japanese Driver's License