After the Honnoji Incident, Sadamasa served Hideyoshi TOYOTOMI as umamawarishu (horse guard) with his foster father, and it is said that he took over the family estate after taking a part in the campaign of Odawara no eki (the Siege of Odawara.)
の本能寺の変後は、養父と豊臣秀吉に馬廻衆として仕え、小田原の役に従軍した頃、家督を継いだとされる。