Shima Onsen: Taxi to Okushimako Lake

I will be going to Shima Onsen and staying in the central town area Shima Tamura Onsen for 1 night. Is there any tour company that can take us tour the upper and lower Shima Onsen area? Or can I hire a taxi to take me round especially to Okushimako Lake? Google map shows that it takes 6 - 10 min to drive from central area but walking will take more than 40 minutes. I am not comfortable to rent a car to drive myself.

Thank you.

Senpaku Kanko Jidosha 浅白観光自動車 has Shima office 四万営業所. Senpaku also has an office in Nakanojo.
https://www.navitime.co.jp/poi?spt=00011.020329282
https://www.google.co.jp/maps/place/%E6%B5%85%E7%99%BD%E8%A6%B3%E5%85%...

You could use Kan-estu Kotsu at Nakanojo.
https://www.google.co.jp/maps/place/%E9%96%A2%E8%B6%8A%E4%BA%A4%E9%80%...

There is the Nakanojo Kanko Guide Volunteer Center at JR Nakanojo. How about to drop at it and ask a negotiation with Senpaku or Kan-estu taxi.
http://www.nakanojo-kanko.jp/pamphlet.pdf#page=14
http://www.nakanojo-kanko.jp/index.html

Or, send an email to info@nakanojo-kanko.jp.
http://www.nakanojo-kanko.jp/english/index.html

If you go to Shima by a direct bus by Kan-estu, then just ask Kan-estu.
http://global.kan-etsu.net/en/express/shima.html

Shima Onsen also has an email, info@shimaonsen.com.
http://www.shimaonsen.com/en/

Thank you very much for the info. I have sent an email to make enquiry, hopefully can get some help.