[Valky]

Originally Posted by KiRa08o2

Spoiler for Answer:

It's not a VN re-play setting, neither something like many sisters (well, actually we can't say anything for now) but more like a "You're my sister"-->"No I'm not! I just 'act' like yours"-->"Ok, too bad". Something like this. Though the MC discovered his supposed "little sister" on volume 4, something in volume 5 kinda...adds suspence.

Spoiler:

So basically all the imoutos are trolling the MC to make him think that they are his imouto?