Tona-Gura!  

Tonari-Gurashi, となグラ！

The Arisaka sisters (Hatsune and Kazuki) and the Kagura siblings (Yuuji and Marie) lived in close proximity when they were younger. They would often play together, even climbing onto each other's verandas from their second-floor windows. Now, ten years have passed, and it seems that Yuuji has become a pervert while Marie is no longer the emotional child she once was.