Bokura no Oukoku
Other names: 僕らの王国, Our Kingdom
Author: Koujima Naduki
Artis: Koujima Naduki
From DMP: Upon the death of his grandmother, country boy Akira Nonaka is taken in by the immensely wealthy and powerful Takatou family. there, he is told that he is a candidate to become next heir to the Takatou name. However, there is another candidate--the princely, handsome Rei, who turns out to be a cousin of Akira's. Far from being competitive, Rei shows no interest in the prospect of inheritance, and instead takes an immediate liking to Akira. Rei's aggressive shows of affection muddle the naive country boy, until Akira begins to discover a budding attraction towards Rei within himself.