Clear Skies!

Clear Skies! (毎日晴天!, Mainichi Seiten!) is a manga series written by Akira Sugano and illustrated by Etsumi Ninomiya. The manga is licensed in North America by Digital Manga Publishing under its Juné imprint, which released the first volume on 28 August 2008.

Plot
It's about four brothers living together, when one of the brother's old high school flame turns up and claims that he's married to the brothers' wild older sister, who is nowhere to be found, bringing his adopted son.