However, after Yoshitatsu SAITO suddenly died in 1561 and his legitimate son Tatsuoki SAITO succeeded the head of the family, kachu of the Saito clan began to split.
しかし、永禄4年（1561年）に斎藤義龍が急死し、嫡男・斎藤龍興が後を継ぐと、斎藤氏は家中で分裂が始まる。