Tactics Ogre: Let Us Cling Together 4-koma Kings - Vol. 1 Ch. 11 - You Expect Me to Laugh About This!?

[MangaDex]

 

[Furuishi]

The King of the Monkeys/Boss of Monkey Mountain thing is a little nuanced. It's basically an insulting expression akin to "big fish in a little pond".

The fairy tale Denam is referring to is Tsuru no Ongaeshi.