[3] Sai occupies the western coastline of Shimokita Peninsula, facing the inlet to Mutsu Bay from the Tsugaru Strait.

Wildlife includes Japanese macaque monkeys, kamoshika, tanuki and Asian black bears.

During the Edo period, it was controlled by the Nambu clan of Morioka Domain and prospered due to its timber industry and as a ferry terminal to Ezo.

Sai has a mayor-council form of government with a directly elected mayor and a unicameral village council of eight members.

Sai is part of Shimokita District which, together with the city of Mutsu, contributes three members to the Aomori Prefectural Assembly.

In terms of national politics, the city is part of Aomori 1st district of the lower house of the Diet of Japan.