Kawaiteru is a very shady and mysterious character, often responsible for some wrongdoings on Yoshi's Island, and has even killed some who 'dare unlawfully set foot in [his] domain.' The one exception would have been Yoshi himself, who seemed to recognise Kawaiteru, and vice versa. This prompted Kawaiteru's response shown above.
"He took quite a few soldiers out, didn't he, your Grandness?"
"He did more than that, Army Hammer Bro. Much, much more than that."
"Oh, yeah. Killed them, took their flesh, ate it, made an undead army of skeletal soldiers."
- Army Hammer Bro. and Bowser talking about the aftermath of the assassination attempt.
Ever since the assassination attempt he has held a large grudge against (and has sworn to be his archnemesis) Army Hammer Bro.
"I will not stop until he is assimilated into my army's ranks!"
Kawaiteru Yosshi is "Dry Yoshi" in Japanese.