From Yen Press:
Sakuta’s shut-in sister, Kaede, has always been content being at home after the bullying incident that put her there. Plus, that’s where her favorite onii-chan is! Yet, slowly but surely, Kaede begins to venture beyond the four walls that protected her these last few years, regaining more and more of the life and freedom the old her knew. But even with Sakuta, Mai, and everyone else in her corner, treating this case of adolescence syndrome isn’t going to be easy.

Based on novel 5.