In 1590, when Masamune DATE was suspected of treason, Kozosu, as Hideyoshi's representative, delivered the letter asking for an explanation and in 1597, she was in charge of managing Hideaki KOBAYAKAWA's transferal from Chikuzen Province to Echizen Province as punishment for his mistake during the Siege of Ulsan.
天正18年（1590年）には謀反の疑いをもたれた伊達政宗に対し秀吉の代理として詰問の書状を送り、慶長2年（1597年）、蔚山城の戦いにおける小早川秀秋の失態で筑前国から越前国への懲罰的移封を決定した際にも、実務を取り仕切っている。