Enables piRNA binding activity. Involved in gamete generation; gene silencing by RNA; and piRNA metabolic process. Acts upstream of or within negative regulation of transposition. Located in nucleus and piP-body. Is expressed in embryo; germ cell of testis; testis; and trunk unsegmented mesenchyme. Orthologous to human PIWIL4 (piwi like RNA-mediated gene silencing 4). [provided by Alliance of Genome Resources, Apr 2022]