The reason why Nobunaga ODA called himself 'Kazusa no suke' and Tadateru MATSUNAGA was appointed to 'Kazusa no suke,' or Masazumi HONDA, Yoshinaka KIRA, and Tadamasa OGURI were appointed to 'Kozuke no suke' was because the use of 'Kazusa no kami' and 'Kozuke no kami' was limited to Imperial Princes, though these titles were only nominal.
織田信長が「上総介」を僭称し松平忠輝が任官し、本多正純、吉良義央、小栗忠順が「上野介」を任官したのも、名目のみとは言え、「上総守」「上野守」の官職が親王のみにしか許されなかったからである。