YOU SAID:
I am riding a bus in Japan
INTO JAPANESE
私は日本でバスに乗っています
BACK INTO ENGLISH
I am on a bus in Japan
INTO JAPANESE
私は日本のバスに乗っています
BACK INTO ENGLISH
I am on a Japanese bus
INTO JAPANESE
私は日本のバスに乗っています
BACK INTO ENGLISH
I am on a Japanese bus
Come on, you can do better than that.