The current version Yandex Translate does not support English to Japanese translation. Here is the full list of valid translation directions:
Azerbaijani-Russian
Belarusian-Bulgarian
Belarusian-Czech
Belarusian-German
Belarusian-English
Belarusian-Spanish
Belarusian-French
Belarusian-Italian
Belarusian-Polish
Belarusian-Romanian
Belarusian-Russian
Belarusian-Serbian
Belarusian-Turkish
Bulgarian-Belarusian
Bulgarian-Russian
Bulgarian-Ukrainian
Catalan-English
Catalan-Russian
Czech-Belarusian
Czech-English
Czech-Russian
Czech-Ukrainian
Danish-English
Danish-Russian
German-Belarusian
German-English
German-Spanish
German-French
German-Italian
German-Russian
German-Turkish
German-Ukrainian
Greek-English
Greek-Russian
English-Belarusian
English-Catalan
English-Czech
English-Danish
English-German
English-Greek
English-Spanish
English-Estonian
English-Finnish
English-French
English-Hungarian
English-Italian
English-Lithuanian
English-Latvian
English-Macedonian
English-Dutch
English-Norwegian
English-Portuguese
English-Russian
English-Slovak
English-Slovenian
English-Albanian
English-Swedish
English-Turkish
English-Ukrainian
Spanish-Belarusian
Spanish-German
Spanish-English
Spanish-Russian
Spanish-Ukrainian
Estonian-English
Estonian-Russian
Finnish-English
Finnish-Russian
French-Belarusian
French-German
French-English
French-Russian
French-Ukrainian
Croatian-Russian
Hungarian-English
Hungarian-Russian
Armenian-Russian
Italian-Belarusian
Italian-German
Italian-English
Italian-Russian
Italian-Ukrainian
Lithuanian-English
Lithuanian-Russian
Latvian-English
Latvian-Russian
Macedonian-English
Macedonian-Russian
Dutch-English
Dutch-Russian
Norwegian-English
Norwegian-Russian
Polish-Belarusian
Polish-Russian
Polish-Ukrainian
Portuguese-English
Portuguese-Russian
Romanian-Belarusian
Romanian-Russian
Romanian-Ukrainian
Russian-Azerbaijani
Russian-Belarusian
Russian-Bulgarian
Russian-Catalan
Russian-Czech
Russian-Danish
Russian-German
Russian-Greek
Russian-English
Russian-Spanish
Russian-Estonian
Russian-Finnish
Russian-French
Russian-Croatian
Russian-Hungarian
Russian-Armenian
Russian-Italian
Russian-Lithuanian
Russian-Latvian
Russian-Macedonian
Russian-Dutch
Russian-Norwegian
Russian-Polish
Russian-Portuguese
Russian-Romanian
Russian-Slovak
Russian-Slovenian
Russian-Albanian
Russian-Serbian
Russian-Swedish
Russian-Turkish
Russian-Ukrainian
Slovak-English
Slovak-Russian
Slovenian-English
Slovenian-Russian
Albanian-English
Albanian-Russian
Serbian-Belarusian
Serbian-Russian
Serbian-Ukrainian
Swedish-English
Swedish-Russian
Turkish-Belarusian
Turkish-German
Turkish-English
Turkish-Russian
Turkish-Ukrainian
Ukrainian-Bulgarian
Ukrainian-Czech
Ukrainian-German
Ukrainian-English
Ukrainian-Spanish
Ukrainian-French
Ukrainian-Italian
Ukrainian-Polish
Ukrainian-Romanian
Ukrainian-Russian
Ukrainian-Serbian
Ukrainian-Turkish
