Transcription factor (By similarity). Binds to DNA sequence motif 5'-CTGTTTCA-3' (PubMed:22819322). Regulates expression of a class of small RNAs, known as 21U-RNAs, perhaps acting redundantly with fkh-4 and fkh-5 (PubMed:22819322). Expressed in most cells of the cleavage stage embryo, apart from a few cells at the posterior pole, from the 20 cell stage to the 200 cell stage. RNAi-mediated knockdown causes significant reduction in the expression of 21U-RNAs, upon simultaneous knockdown of fkh-4 and fkh-5.