Catalyzes the NADPH-dependent reduction of 1,5-anhydro-D-fructose (AF) to 1,5-anhydro-D-glucitol (By similarity). Has low NADPH-dependent reductase activity towards 9,10-phenanthrenequinone (in vitro) (PubMed:12604216, PubMed:15118078). 1,5-anhydro-D-glucitol + NADP(+) = 1,5-anhydro-D-fructose + H(+) + NADPH Inhibited by p-chloromercuribenzoic acid and alkyliodines. Monomer. Specifically expressed in testis (PubMed:12604216, PubMed:15118078). Expressed in testicular germ cells and testis interstitial cells (PubMed:15118078). Belongs to the aldo/keto reductase family.