It is thought to be in the time of Nobukiyo BOMON and Takakiyo BOMON, Nobutaka's sons, that "Bomon" was first used as a family name, but in any case, the substance of the matter is that Nobutaka can be called the founder of the Bomon family.
坊門を家号としたのは信隆の子の坊門信清と坊門隆清の代からとされるが、実質的には信隆が坊門家の祖であると言える。