Mt.Inasa access incoming winter January 2016

I have planned to visit Nagasaki and check out the great city view at the top of Mt.Inasa in next year, January which rope way is still unable to use.
And I knew that bus riding to the top of Inasa was available only from March 15th to December 15th as well, so how can I access there if I don't choose taxi?
Thank you.

No, bus operated everynight until 5 Feb from Nagasaki station's bus stop.
http://www.nbkanko.com/publics/index/111/&anchor_link=page111_229_382
Adult(大人) : 1000Y
Ｎeed booking by Call. (No online reservation)

But this bus is not oneway round type with short stay.
Nagasaki station -(20min)- Mt.Inasa observation deck(30min) -(20min/back way)- Nagasaki station
So if need stay longer as over 30min take a taxi about 2000Y/oneway from/to Nagasaki station.

Anyway send e-mail recommend.
http://travel.at-nagasaki.jp/en/transportation/
(jump to page bottom right "Contact us")

Thank you for your help.
That's very helpful, I will try it!