After that in 1575, Motochika, completing the unification of Tosa after the Battle of Shimanto-gawa River, through the connection with Hidemitsu, who became a senior vassal of Nobunaga, was given a letter of Nobu (信) as eboshioya (a person who put on an eboshi in the case of genpuku ceremony) of Yasaburo (later Nobuchika), legitimate son of Nobunaga, and also was given a permission to freely conquer other provinces in Shikoku.
その後1575年、四万十川の戦いで土佐を統一した元親は信長の重臣となった光秀を通じて、嫡男の弥三郎（後の信親）の烏帽子親として信の一字と、四国の切り取り自由の許可を貰った。