Lysine demethylase that demethylates both histones and non-histone proteins. Mediates demethylation of dimethylated 'Lys-9' of histone H3 (H3K9me2). Recruited to trimethylated 'Lys-4' of histone H3 (H3K4me3) at rDNA promoters and promotes expression of rDNA (By similarity). Belongs to the JHDM1 histone demethylase family. JHDM1D subfamily. In contrast to the related histone demethylases jhdm1d and phf8, the conserved active His in position 321 is replaced by an Asn. However, the presence of an Asn residue neither affects binding to the catalytic iron nor abolishes demethylase activity.