Otoro Onsen to Memanbetsu airport

I will be going to Abashiri, then Otoro Onsen in mid September . I plan to take a flight from Memanbetsu Airport to Tokyo after spending two days in Otoro Onsen. How do I go from Otoro Onsen to Memanbetsu Airport? Are there buses? I understand that Shiretoko Airport Liner runs till March. What about September?

This is last year 2014 summer dia bus table[PDF] 14 June to 13 Oct.
http://www.sharibus.co.jp/pdf/ShiretokoAirPortLiner26.06.14.pdf
女満別空港 : air port
ウトロ温泉 Utoro onsen (NOT "Otoro")

No big diffrent maybe.
Send e-mail to bus companay?
http://www.sharibus.co.jp/contact.html

Last year summer dia[夏期ダイヤ] info updated 1 Apr.
http://www.t-ars.net/blog/blog.cgi?n=20
http://www.sharibus.co.jp/index.html

Thank you. I will email the Sharibus Co and hope to get an answer. From last year's time table, there are special buses starting from UTORO Onsen. Do you know where I can buy the bus ticket? Can I buy the ticket at the Utoro Onsen bus station?