The girl who was hiding behind the shadows and peeping at Shiro was none other than the other girl whom Shiro had saved earlier when he was actually saving Silvia.
It seemed like she wanted to say something but couldn't bring herself to say that.
Now he completely understood that the boy who was sitting beside him was her brother and the girl about whom he was mentioning was none other than his sister.
"Haha, so you are her brother?", while saying this he waved his hands towards the girl who was trying to hide.
'Oh no! He spotted me!', she thought.
He could then understand that the boy was just worried about his sister's well being and he didn't want her to be sad and probably that was why he said that.
But the boy too didn't know Shiro's powers and maybe that was why he concluded th