Zettai Ni Tokimeite Wa Ikenai!

From Lemonade Scans:
Sakura confesses to Hatano-kun one summer and is rejected instantly, but does not have time to fall into the depression that returns to her house to meet her new · “Younger brother”. What she never expected her “little brother” ended up being bigger than her … How can you carry out now on more Kaede and Sakura