The bank is relatively small, even among Japanese regional banks; it operates primarily in Yamagata, though it also operates branches in Sendai, Tomiya, Fukushima, Akita in neighboring prefectures, as well as in the capital of Tokyo.

Unlike common banking practices, Shogin, as the bank is abbreviated in Japanese, maintains full teller-supported services on the weekends and holidays at all its branches.

On March 9, 2004, the government-sponsored Shoko Chukin Bank, a financial institution that provides credit and loans to small and medium-sized enterprises, announced that it would carry out limited business cooperation with the bank in order to serve the small and medium enterprises of that area.

In February 2024, Fidea Holdings announced that a committee had been set up to investigate the merger of the bank with Hokuto Bank, another Fidea owned institution.

In November, a merger scheduled for 1 January 2027 was announced, with Shonai continuing and Hokuto dissolving.