Route 275, from Tobetsu to Shintotsukawa and Uryu, these areas are the most beautiful country with rice field.
Going to Asahikawa from Sapporo by car, It is popular to run on route 12 via Iwamizawa and Takikawa. I think route 12 is heavy traffic and many signals that make me more anxious or nervous.
But route 275, it is a country road and minimum signals and not much traffic and more, beautiful scenery from Spring to Autumn. This is an unknown and another route you would choose.
Clear sky in the summer, you might run by bike. This is a nice and superior choice you enjoy entire Hokkaido.