Chōshi is a city located in Chiba Prefecture, Japan. As of 1 December 2020, the city had an estimated population of 59,174 in 27,160 households and a population density of 700 inhabitants per square kilometre (1,800/sq mi). The total area of the city is 84.19 km2 (32.5 sq mi).

The Tone River is a river in the Kantō region of Japan. It is 322 kilometers (200 mi) in length and has a drainage area of 16,840 square kilometers (6,500 sq mi). It is nicknamed Bandō Tarō ; Bandō is an obsolete alias of the Kantō Region, and Tarō is a popular given name for an oldest son. It is regarded as one of the "Three Greatest Rivers" of Japan, the others being the Yoshino in Shikoku and the Chikugo in Kyūshū.