GO:0032454:   histone demethylase activity (H3-K9 specific)
Catalysis of the reaction: histone H3 N6-methyl-L-lysine (position 9) + alpha-ketoglutarate + O2 = succinate + CO2 + formaldehyde + lysine. This reaction is the removal of a methyl group from lysine at position 9 of the histone H3 protein.