YOU SAID:

I have to be on a bus in 4hrs

INTO JAPANESE

私は4時間後にバスに乗らなければなりません

BACK INTO ENGLISH

I have to catch the bus in 4 hours

INTO JAPANESE

4時間でバスに乗らなければならない

BACK INTO ENGLISH

I have to catch a bus in 4 hours

INTO JAPANESE

4時間でバスに乗らなければならない

BACK INTO ENGLISH

I have to catch a bus in 4 hours