Hokkaidō in the context of "Teshio Mountains"

The Fuhanken Sanchisei (府藩県三治制; "Fu, Han and Ken three-tiered Governance System") was the subnational government structure in early Meiji Japan. It lasted from the Boshin War, the start to the Meiji Restoration, in 1868 until the replacement of all remaining feudal domains (-han) with prefectures (-ken) in 1871. During this period, prefectures, urban prefectures (府, fu) and rural prefectures (県, ken), controlled by the new central government, and daimyō Domains (藩, han), still under their pre-restoration feudal rulers, formed the primary administrative subdivisions of the country. The exact numbers varied continually as adjustments to the feudal territorial divisions, mergers and splits started to take up pace, but very roughly there were about >250 -han and about <50 -fu/-ken in total during this time.

As the political borders changed all the time, ancient ritsuryō provinces, essentially static except for some modernizing adjustments in the North where the giant provinces of Mutsu and Dewa (both Tōsan Circuit) were split up and a new circuit (Hokkai Circuit) with 10 provinces was added on Ezo, remained the primary geographic frame of reference even in Meiji Japan until around the turn of the century – just as they had been throughout the late Middle Ages and early modern period.

The Northeastern Japan Arc, also Northeastern Honshū Arc, is an island arc on the Pacific Ring of Fire. The arc runs north to south along the Tōhoku region of Honshū, Japan. It is the result of the subduction of the Pacific plate underneath the Okhotsk plate at the Japan Trench. The southern end of the arc converges with the Southwestern Japan Arc and the Izu–Bonin–Mariana Arc at the Fossa Magna (ja) at the east end of the Itoigawa-Shizuoka Tectonic Line (ITIL). This is the geologic border between eastern and western Honshū. Mount Fuji is at the point where these three arcs meet. To the north, the Northeastern Japan arc extends through the Oshima Peninsula of Hokkaidō. The arc converges in a collision zone with the Sakhalin Island Arc and the Kuril Island Arc in the volcanic Ishikari Mountains of central Hokkaidō. This collision formed the Teshio and Yūbari Mountains.

The Ōu Mountains form the backbone of the volcanic part of the inner arc that run from Natsudomari Peninsula in Aomori Prefecture south to Mount Nikkō-Shirane in Tochigi and Gunma prefectures. The volcanic front consists of four north to south lines of Quaternary volcanoes and calderas, which extend the length of the range. It also includes the Quaternary volcanoes of southwestern Hokkaido. The Dewa Mountains and the Iide Mountains are non-volcanic uplift ranges that run parallel to the west of the Ōu Mountains.

The Nemuro Peninsula (根室半島 Nemuro-hantō) is a peninsula which extends from the east coast of Hokkaidō, Japan. It is some 30 kilometres (19 mi) long and 8 kilometres (5.0 mi) wide, and forms part of Nemuro City. Cape Nosappu at its tip is the easternmost point of Hokkaidō. The northern coastline is on Nemuro Bay, while the south faces the Pacific Ocean. Islands of the Habomai (Khabomai) Archipelago, administered by Russia but claimed by Japan, extend eastward from the peninsula.

The Ishikari Mountains (石狩山地, Ishikari Sanchi) is a range of volcanic mountains in central Hokkaidō, Japan. The mountain range is made up from the Daisetsuzan Volcanic Group and the Tomuraushi Volcanic Group. The volcanoes are part of the Kurile arc of the Ring of Fire. The mountains are also referred to as Kamui Mintara which is an Ainu name meaning “the playground of the gods”.

A somma volcano, also known as a sommian, is a volcanic caldera that has been partially filled by a new central cone. The type is named after Mount Somma ("Summit"), a stratovolcano in southern Italy with a summit caldera in which the upper cone of Mount Vesuvius has grown. Other examples of somma volcanoes can be found on Russia's Kamchatka Peninsula and the Kuril Islands, stretching south from Kamchatka to Hokkaidō, Japan.

Some examples of somma volcanoes are the following:

Papilio xuthus, the Asian swallowtail, Chinese yellow swallowtail, Japanese Swallowtail, Korean Swallowtail or Xuthus swallowtail, is a yellow-colored, medium to large sized swallowtail butterfly found in northeast Asia, northern Myanmar, southern China, Taiwan, the Korean Peninsula, Japan (from Hokkaidō to the Yaeyama Islands), Siberia and the Hawaiian Islands. The butterfly has been observed thrice in New Zealand. Once in Dunedin in 1996 emerging from a chrysalis in a car yard specializing in Japanese used cars; it is thought the chrysalis arrived through one of the cars. and later in Auckland in 2011 and 2016. It was also recorded in the state of Arunachal Pradesh, India, in 2014.

It mates multiple times in its life, leading to an increased genetic diversity in its young. It is preyed upon by a host of organisms, including the tree cricket Oecanthus longicauda, ant Lasius niger, and wasps (Polistes and Trogus mactator). P. xuthus utilizes color vision and color constancy while foraging for plants of the family Rutaceae.

The Tsugaru Peninsula (津軽半島, Tsugaru Hantō) is a peninsula in Aomori Prefecture, at the northern end of Honshū island, Japan. The peninsula projects north into the Tsugaru Strait separating Honshū from Hokkaidō. The western coast is on the Sea of Japan, while on its eastern coast are Aomori Bay and Mutsu Bay. The peninsula is bisected from Cape Tappi at its northern end to the Hakkōda Mountains on its southern end by the Tsugaru Mountains. Across the Tsugaru strait to the north is Hokkaidō's Matsumae Peninsula, to which it is linked by the Seikan Tunnel.

Cape Nosappu (納沙布岬, Nosappu-misaki) is a point on the Nemuro Peninsula, Nemuro, Japan, which is the easternmost point in Hokkaidō. It is also the easternmost point in Japan which is open to the public. It is located where the waters from the Pacific Ocean meet those from the Sea of Okhotsk. The Cape Nosappu Lighthouse is the oldest in Hokkaidō, built in 1872.

The cape is very close to the Habomai Archipelago, which is administered by Russia. The closest island, Signalny Rock, is just 3.7 km away. As such, Russian patrol boats frequently appear on the strait. However, Japan claims the sovereignty over these islands. (See Kuril Islands dispute.) Consequently, the cape houses a lot of monuments dealing with Japanese claims on the territories, such as the House of Nostalgia for the Homeland, the Bridge on the Four Islands, and others.