If you mean YOUR brother or sister. 兄 ani - older brother 姉 ane - older sister 弟 oto:to - yonger brother 妹 imo:to - yonder sister If you say about another person's brother or sister お兄さん oniisan - older brother お姉さん one:san -older sister 弟さん oto:tosan - yonger brother 妹さん imo:tosan - yonder sister

In the conversation between you and your sister or brother, we call お兄ちゃん(oni:chan/ older brother) お姉ちゃん( one:chan / older sister) and they all you ( if you are younger sister or younger brother) by your name. But we won't call them like this when you talk with others about your sister and brother, you call them like Metalgreg said.