Bus reservation from Hakata to Takachiho

Can anyone advice how do I make a reservation for the above ? Can I go direct to the Hakata bus terminal and make reservation for the following day ? (As I cannot find any English web site for reservation.)
Thank you for all your help.

http://www.nishitetsu.jp/en/highway_bus/
http://www.atbus-de.com.e.jo.hp.transer.com/
Hakata is Fukuoka[福岡] .pf
Takachiho is Miyazaki[宮崎] .pf

Bus name is "Gokase-go[ごかせ号]" for Nobeoka[延岡].
http://www.nishitetsu.jp/bus/highwaybus/rosen/gokase.html
[PDF] time table
http://www.nishitetsu.jp/docs/bus/highwaybus/guide/jikokuhyo/gokase.pd...
Takachiho[高千穂] is not last stop.
博多バスターミナル : Hakata bus terminal
高千穂バスセンター : Takachiho bus center/centre.
4020Y / oneway no discount regular fare. (運賃表 fare table)
7200Y / round discount (valid for 10 days from dep date)
12860Y / four oneway tickets set discount. (valid for 6 month)
Booking possible until on the day dep time if not full already.

Bus dep No.35 stop (3F)
http://www.f-kc.jp/bus/stop_guide.html
http://www.f-kc.jp/etc/access.html
(Hakata guchi[博多口] exit out and turn right)

http://www.nishitetsu.jp/en/contact/index.html

Thank you so much for the information provided.