YOU SAID:
into japanese then back into english
INTO JAPANESE
日本語にしてから英語に戻す
BACK INTO ENGLISH
Change to Japanese then change back to English
INTO JAPANESE
日本語に切り替えてから英語に戻す
BACK INTO ENGLISH
Switch to Japanese and back to English
INTO JAPANESE
日本語に切り替えて英語に戻る
BACK INTO ENGLISH
Switch to Japanese and back to English
You've done this before, haven't you.