This is said to have essentially signified a break away by the Imagawa family from the control of the Muromachi shogunate and a change in their position from Shugo Daimyo (Provincial Daimyo) to Sengoku Daimyo (Daimyo in Sengoku period).
これによって今川家は事実上室町幕府からの統制を離れて守護大名から戦国大名の段階へ移ったと言われている。