Yes,I'm sure we all want to ask that same question!Why is takua half blue and half red?What happened?Is he simply half Ga-koronan?No!if he was half Ga-koronan,then he would be half boy,half girl!So what happened?Its ur chance to make your oppinion on this one!What do you think?

Well I think he was made that way to separate him from the other matoran.

right now that remains a mystery why takua has a blue mask,i think that was just the way he was created,and thats why the other matoran made fun of him,because his mask was differant from theres.