Tohoku refers to the northeastern region of Honshu, Japan, which consists of seven prefectures: Aomori, Iwate, Miyagi, Akita, Yamagata, Fukushima, and Niigata.
You can reach Miyagi and Fukushima prefectures from Tokyo in just 90 minutes using the shinkansen (bullet train). You can also access Aomori Prefecture from Hakodate (Hokkaido) in only 60 minutes.