http://ha3.seikyou.ne.jp/home/sewatari/bustime/tanba/tankai3.jpg
"Tango kairiku kotsu(丹後海陸交通)" is the official name of the bus company in this region.
Although usually people call it "Tankai basu(丹海バス)".
Their official website http://www.tankai.jp/ (in Japanese)
You can find the bus schedule&fare on Google map(in English).