A monkey escaped from a nearby zoo, Big Bro turned a corner, saw the monkey picking up the phone, yelled "stop that's my sis phone". Monkey got scared, took off with the phone into the bushes, Big bro gave chase.
@earl It's the "ended up in another world fighting the strongest Demon Lord in history" part while searching for a phone which I found peculiar. It sounds like the demon king in question stole the phone
This is a simple and cute chapter. Also, this author knows how to write compelling wincest romance: there's nothing like a brother going through hell just to bring a pure smile back to his imouto's face.