Kurobe Gorge Railway (Train Ride)

I am planning to reserve tickets for the Kurobe Gorge Railway this November and in the website round trip ticket is a must. If I will reserve the Unazuki to Keyakidaira (round trip) does this mean we can get on and off the train in every stations or we need to just stay on the train until it reached Keyakidaira Station? Do we need to change trains to reach Keyakidaira Station? Can someone please give me an idea on how the trip will go about before I book tickets. Thank you and I am looking forward to your replies.

I am planning to reserve tickets for the Kurobe Gorge Railway this November and in the website round trip ticket is a must.

Round trip tickets are not a must. As a matter of fact, if you plan to get on and off along the way, you cannot use a round trip ticket for the entire way, but should buy tickets for each section traveled.

If I will reserve the Unazuki to Keyakidaira (round trip) does this mean we can get on and off the train in every stations or we need to just stay on the train until it reached Keyakidaira Station?

You cannot get on and off along the way. You need to stay on the train until it reached Keyakidaira, otherwise the ticket becomes invalid for the rest of the leg.

If you want to get on and off along the way, then you can make online reservations only for the first part. The other tickets from there have to be purchased on the day as you go. That is quite easy on regular days when there are always some vacancies on the next train, but it can theoretically cause some waiting times on busy days when some trains may be full.