I took “Resort Asunaro” hybrid diesel multiple unit train yesterday.
This type of train is operated in Aomori prefecture, and you can transfer from the Shinkansen superexpress trains to “Resort Asunaro” at Hachinohe Station or Shin-Aomori staiton.
It takes approximately 3 hours from Tokyo to Hachinohe/Shin-Aomori by the Shinkansen trains.
