Catalyzes the NADPH-dependent reduction of 1,5-anhydro-D-fructose (AF) to 1,5-anhydro-D-glucitol. 1,5-anhydro-D-glucitol + NADP(+) = 1,5-anhydro-D-fructose + H(+) + NADPH Inhibited by p-chloromercuribenzoic acid and alkyliodines. Monomer. Belongs to the aldo/keto reductase family.