[1] With the conversion of the Seikan Tunnel from conventional trains into the Hokkaido Shinkansen, this route has seen a resurgence in ridership as the cheaper alternative.

Aside from the current routes, the Higashi Nihon Ferry also operated a wide network connecting Muroran, Tomakomai, and Iwanai to the north; Sendai, Hachinohe, Ōarai, and Jōetsu to the south; and Busan, South Korea.

In October 2000, Dōnan Jidōsha Ferry began operating passenger services with a newly built ship, the Esan 2000.

[8] In November 2008, Higashi Nihon Ferry suspended its Hakodate—Aomori, Hakodate—Ōma, and Muroran—Aomori services and sold three ships (Venus, Virgo, and Vayu) to Dōnan Jidōsha Ferry.

[9] Dōnan Jidōsha Ferry, however, chose not to operate the Muroran—Aomori route.