After that, he still had a struggle against Korenaga and his son Koresaki ASO, and in 1543 he captured Katashida-jo Castle and put Koresaki to rout and practically put an end to a division among the Aso clan over thirty years.
その後も惟長とその子阿蘇惟前と抗争を繰り広げ、1543年に堅志田城を落として惟前を敗走させ、30年に及んだ阿蘇氏の分裂に事実上の終止符を打った。