It is said this was because after Odawara no Jin (The Siege of Odawara) Hideyoshi suddenly confiscated the five territories Ieyasu had spent decades gaining the hard way (Mikawa, Totomi, Suruga, Kai and Shinano provinces), and gave him seven former Gohojo clan territories (Musashi, Izu, Sagami, Kozuke, Shimotsuke, Kazusa and Shimousa provinces) instead, which Naomasa regarded as unsatisfactory.
その理由は、小田原の陣の後、突然、秀吉が家康が何十年間も苦労して手に入れた三河国、遠江国、駿河国、甲斐国、信濃国の5カ国の領地を没収して、その代わりに後北条氏の旧領である武蔵国、伊豆国、相模国、上野国、下野国、上総国、下総国の7カ国に移封したことを不満に思っていたためだと言われている。