The Bungo Channel, which separates Kyushu and Shikoku, runs along the west of Ōtsuki, while the Kuroshio Current brushes up against its south shores.

[6] Ōtsuki has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light snowfall.

[10] Signs of human presence, including stone knives and tools, date back as far as the Japanese Paleolithic,approximately 20,000 years ago.

[13] During the Edo period, the area was part of the holdings of Tosa Domain ruled by the Yamauchi clan from their seat at Kōchi Castle.

Ōtsuki has a mayor-council form of government with a directly elected mayor and a unicameral town council of ten members.

In terms of national politics, the town is part of Kōchi 2nd district of the lower house of the Diet of Japan.

A massive fire occurred in the fishing village of Komame (古満目), and to prevent a similar catastrophe from reoccurring, a ritual to be carried out each new year was prescribed.

[26] In the modern day, this ritual is carried out every year on January 2, and includes elders making offerings at several locations in the village while young men sit waiting outside wearing only simple yukatas.

After 2 to 3 hours of enduring the cold and making prayers to ward off disaster, the event comes to a close as families prepare warm baths to reinvigorate the freezing participants.