Japanese kaibokan and the late start in escort construction

Did the Imperial Japanese Navy have dedicated escorts comparable to Flower-class corvettes or Black Swan-class sloops, and how effective was that provision?

Japan had kaibokan escort or sea-defense ships, including purpose-built classes, but too few were built and construction began too late for the scale of the requirement.

Kaibokan were escort or sea-defense ships, a role also filled for a time by older vessels removed from frontline combat duties. Japan eventually built dedicated classes, but the programmes are criticized as too small and too late. The Shimushu class is dated to construction between 1939 and 1941. Four ships were built against a plan for sixteen. At under 900 tons standard and 19.7 knots, without torpedoes, the design fits the escort limits discussed here: below 2,000 tons and no more than 20 knots. Its weapons included depth charges and throwers, a mortar, 4.7-inch guns and Type 96 weapons. The comparison with sustained British corvette construction supports the argument that Japan should have been building such escorts each year from around 1930. The criticism concerns escort provision, with no detailed assessment of individual engagements.