Initially, Masatsugu's grandson Sadatsugu OIKAWA became a retainer of the KASAI clan in the earliest time, but he was exterminated due to the reasons described below.
まず政嗣の孫・及川定嗣がもっとも早期に葛西氏の家臣となっているが下に述べるようにのちに滅ぼされた。