How to see Rapeseed at Yotei mountain

I'm from Thailand and will go to Hokkaido on 1-9th of June, 2015. I'll travel with JR Hokkaido pass and wish to see the Rapeseed at Yotei mountain at Niseko but I haven't found a location of this flower field from Niseko station or the best way of transport to this. Please recommend what the most comfortable way. Thank you!

At 西山花の丘[Nishiyama? hana no oka(west mountain flower hill)] is so.
http://www.niseko-ta.jp/index.php?id=137
This map's "西山の花畑(nishiyama no hana batake)" is so.
http://sahina-mulberry.com/sahina/img/sahina_map_2000.jpg


Bike(cycle) rent enough from JR Niseko stn.

http://www.ekinavi-net.jp/hokkaido/shiribeshi/niseko/info.html
http://www.town.niseko.lg.jp/event/Green%20Bike%20Flyer.pdf

Rapeseed flower name is "Kigarashi[キガラシ]" group of Nanohana[菜の花].
But most Japanese didn't know this flower name usual
Nanohana is nation wide very famous same yellow color field
as one of spring sign flower and food of tenupra or ohitashi.
So kigarashi is not blooming in Spring season one of early summer flower in Hokkaido.
This is largest nonahana field in Hokkaido Takikawa city around late May.
http://www.pref.hokkaido.lg.jp/ss/ckk/2405_tobu_photo.JPG