A regional bank (chihō ginkō 地方銀行 or chigin 地銀) is a Japanese term for one of the 100 banks who are members of the Regional Banks Association of Japan (zenkoku chihōginkō kyōkai 全国地方銀行協会). They usually have their head office in the capital city of one of the 47 prefectures of Japan, serving mainly its local prefectural customers. Historically, regional banks in the same areas tend to merge over time, reducing overheads while increasing their strength and regional footprint.