Yukimura wasn't fond of the way others looked at his dragon. He was very aware of how attractive he was. His disposition called people towards him. At times it seemed as if he either didn't notice it or was just being polite.
It left Yukimura feeling a bit possessive. There were times when everyone could be sitting and talking and he could see the glint in one of their eyes as they talked to Masamune. That was when he would wrap himself around the other from behind. He'd nuzzle Masamune's neck and growl like the tiger he is.
Masamune found it to be entertaining, and he would turn his face to smile at the other. A hand would rest itself on Yukimura's bicep as if to tell him not to worry.
At the end of the day. Yukimura knew that if someone were to actually come on to him he would shut them down immediately. He'd seen him to do it to Chosokabe on multiple occasions.
Masamune loved only him, and only accepted his advances. Yukimura knew he had nothing to worry about, but he felt better when he was able to intimidate the other suitors.