The 18th Infantry Regiment Hohei Dai-Ju-hachi Rentai was an infantry regiment in the Imperial Japanese Army (IJA). Its call sign and unit code was Thunder-3219 . The unit was formed in 1884 and based in the city of Toyohashi as a branch of the Nagoya Garrison. Throughout its history, the majority of its soldiers came from the Mikawa region, or eastern Aichi prefecture.

Toyohashi is a city in Aichi Prefecture, Japan. As of 1 December 2019, the city had an estimated population of 377,453 in 160,516 households and a population density of 1,400 persons per km2. The total area of the city was 261.86 square kilometres (101.10 sq mi). By area, Toyohashi was Aichi Prefecture's second-largest city until March 31, 2005 when it was surpassed by the city of Toyota, which had merged with six peripheral municipalities.