YOU SAID:

hi this is my sister that works at my office

INTO JAPANESE

こんにちはこれは私のオフィスで働いている私の妹です

BACK INTO ENGLISH

Hello, this is my sister working in my office

INTO JAPANESE

こんにちは、これは私のオフィスで働いている私の妹です

BACK INTO ENGLISH

Hi, this is my sister working at my office

INTO JAPANESE

こんにちは、これは私のオフィスで働いている私の妹です

BACK INTO ENGLISH

Hi, this is my sister working at my office