Isamu was a ronin leader of the Guards' Wrath. A pious man, he meditated upon the convenience to build a temple. Isamu ordered to build in their permanent camp a Temple to Mikoto. He claimed that thanks to the blessings of Mikoto, the Fortune of Ronin, and him alone that the Guards had survived as long and as well as they did. The monks who arrived to tend the temple called the settlement Porisuko in honor of the original founder of the Guards, Porisu.