Ieyasu felt that Nobushige, who was most active among warlords on the Osaka side, was dangerous and ordered Nobushige's older brother Nobuyuki SANADA to persuade Nobushige to switch sides for 400,000 koku of Shinano Province, but he wasn't interested in this preferential condition at all and persisted in his loyalty to the Toyotomi family (according to one theory, Ieyasu ordered Nobushige's uncle Nobutada SANADA and offered 100,000 koku of Ueda).
家康は大坂方の諸将の中で最も活躍した信繁に脅威を覚え、大坂冬の陣の後には信繁の兄真田信之に命じて信濃一国40万石で彼を調略しようとしているが、この破格の条件に興味を微塵も見せず豊臣家への忠誠を最期まで貫き通している（一説には叔父真田信尹に命じて上田10万石とも）。