Watashi no futago ni arigato(Thank you my twin)

This story is about a little girl named Kisho mamiko(14)who can't speak live with her big brother named Kisho mamoru(14).They lived alone when an accident occurs on their parents when they're 12 year old.Now,their lives have changed since their friends are on their side and always keep them happy.But....one day..one of them had to go when a car hit them and they had be taken to hospital...

Mamiko...or...Mamoru?