The reason was not only because Mibu was too cramped as the members grew in number, but also because West Hongan-ji Temple had strong loyalty to the Emperor and had close relationship with the Mori family of Choshu Domain.
隊士が増え手狭になったこともあるが、西本願寺は勤王の色濃く、長州藩毛利家と関係が親密な寺であったためである。