premise: Johan Niemann (born 26 June 1977) is best known for being the current bass player for Evergrey and co-founding the band Mind's Eye, for membership of Swedish heavy metal band Therion and as a member of the Scandinavian theatrical metal band Evil Masquerade. He is also currently live guitarist for Tiamat. He is a brother of Kristian Niemann.
hypothesis: Johan Niemann's brother is a musician 
reason: Based on the information from the agent, we know that Johan Niemann has a brother. It talks about this after discussing Johan's music accomplishments, so it is possible that his brother plays music with him, but it is not revealed for certainty. 