YOU SAID:

One thing, I don't know why

INTO JAPANESE

一つ、理由が分からない

BACK INTO ENGLISH

I don't know the reason

INTO JAPANESE

理由がわからない

BACK INTO ENGLISH

I don't know why

INTO JAPANESE

どうしてか分からない

BACK INTO ENGLISH

I don't know why.

INTO JAPANESE

どうしてか分からない

BACK INTO ENGLISH

I don't know why.