Katsutoyo himself initially worked for the lord of Kariyasukajo Castle (Ichinomiya City) Masasada AZAI, and the lord of Matsukurajo Castle (Owari Province) (Kakamigahara City, Gifu Prefecture) Nagayasu MAENO, then left Owari and worked for the lord of Makimurajo Castle in Mino Province (Anpachi-cho, Anpachi-gun, Gifu Prefecture) Masatomo MAKIMURA, and the lord of Omi Province Seta-jo Castle (Otsu City, Shiga Prefecture) Kagetaka YAMAOKA.
一豊自身は当初は苅安賀城（一宮市）主・浅井政貞、松倉城(尾張国)（岐阜県各務原市）主・前野長康、その後尾張を出て美濃国牧村城（岐阜県安八郡安八町）主・牧村政倫や近江国勢多城（滋賀県大津市）主・山岡景隆に仕えるなどした。