Ima wa Mada "Osananajimi no Imouto" Desu kedo. - Vol. 1 Ch. 4

[MangaDex]

 

[HoangDinh]

lol plot twist

 

[HoangDinh]

lol plot twist

Well, more like a big reveal for all the cryptic shit that was being hinted at in chapter 1

 

[rmremail]

My prediction: It wasn't the younger sister that died, but the older one.

That's why the MC is so emotionally withdrawn - the girl he loved died.