Sono Yo no Dokoka, Chizu ni Nai Kuni

Filled with wanderlust, Shin parachutes into the completely isolated and uncharted kingdom of Oraie. In this mysterious land, Shin meets the noble child king, Master Mustia, and his retainer, the beautiful, graceful, and cool None.
Shin sees None repeatedly kiss Master Mustia as a form of "medical treatment" to save him from a fatal lung disease known only to Oraie. But, what will Shin do when faced with the overwhelming force of None's repressed passion? Will there ever come a day when master and servant can share a romantic kiss to express their maddening love for each other? Drawn with the full might of Nikke Taino, this is the story of a beautiful predestined romance in a tiny imaginary country.

(Source: Renta!)