Guess it depends then...The bike need to be boxed or bagged to take it on a bus....done it loads of times.
Actually, I've carried a bike in a box on the limousine bus from Narita. I paid an additonal baggage charge of 1000yen.Most highway bus companies wont allow bulky items like bike bags/boxes. Carraige of bicycles is also forbidden. Even airport limousine buses dont allow them