Rainy Brother 3 (霧雨兄弟の三男, Kirisame Kyōdai no Sannan) is a Shadow in the series.
Rainy Brother 3 can be found on the 5th and 6th floors of Marukyu Striptease. It may drop the 3rd Boy's Talc when defeated. Selling this will unlock the Downpour Sword for the protagonist, which will boast the highest damage for several dungeons along with a heightened Critical Rate, but only has a Hit rating of 50.
-Rainy Brother 3 appears to have been inexplicably removed in Persona 4 Golden, making the Downpour Sword impossible to acquire in said version of the game.