During the Muromachi period, this custom was even diffused among adults amongst the common people, moreover, during the Sengoku period (period of Warring States) of Japan, it was done as a symbol of being an adult for bushos' (Japanese military commanders) daughters at the age around 8 to 10, at that time, the wife of a guardian relative was called kaneoya (godmother of kanetsuke).
室町時代には一般の大人にも浸透したが、戦国時代(日本)に入ると政略結婚に備えて8～10歳前後の戦国武将の息女へ成年の印として鉄漿付けを行ない、このとき鉄漿付けする後見の親族の夫人を鉄漿親(かねおや)といった。