The Ha-Go model 1 (Seha-tei) was a prototype escort gunboat developed to replace the Soukou-tei and better support Japanese Daihatsu-class landing ships. Two versions were developed: the Model 1 (Seha-tei), which was larger and featured a more powerful 150 horsepower engine, and the Model 2 (Seni-tei), which was designed to be easier to manufacture. The Model 2 prototype was completed in October 1944, followed by the Model 1 in December of the same year. Despite the prototypes being finished, neither boat entered serial production and both were decommissioned after Japan's surrender.

Ha-Go (mod. 1) was introduced into the game in Update 1.89 "Imperial Navy". This compact escort gunboat is armed with a 57 mm tank gun, found on the I-Go and Chi-Ha, which, despite its low velocity and range for coastal combat, delivers solid firepower. Additionally, it features dual-mounted 20 mm guns, offering substantial damage per second. While its gun characteristics may limit its range, the Ha-Go (mod. 1) compensates with its close-range punch and versatile armament.