Complex sentence: Ryu is a wandering martial artist and expert of the Yamasenken; when he was 6 years old he and his father were a very poor family who owned the shoddy Kumon Dojo.
Split into simpler sentences: Ryu is a wandering martial artist and expert of the Yamasenken. When he was 6 years old, he and his father were a very poor family that owned the shoddy Kumon Dojo.