Thank you very much for your prompt reply, William 512. I have 2 further questions:
(1) Is it required of us to reserve the bus tickets in advance?
(2) Looking at the walking course map of Oirase stream, I should be sitting on the left side of the bus (coming from Aomori) as this faces the stream?
When we took the bus during Feb (winter service nowadays is suspended) we booked our seats beforehand but the bus was less than half full on the day of travel. By autumn foliage season you can expect a lot more visitors, so it would be safer if you book your seat in advance.
Going towards Towada-ko you should sit on the right-hand side for view of Oirase Stream.
Thanks again for your help, William512.
Thanks for your help, can I ask how did you go about booking your tickets? I'm going during october and my travel connection times are quite tight and so I'm keen to book my tickets prior to the day of travel in case it is busy!
We bought our tickets in advance in Sendai JR station a few days beforehand. It was in 2009 when the bus was still operating during winter months, so not sure if the ticket reservation procedures nowadays have changed or not !
Hopefully OP sees this and will respond with update information. Send a PM to get his/her attention.