Catalyzes the NADPH-specific reduction of 1,5-anhydro-D-fructose to 1,5-anhydro-D-mannitol. Also shows some activity against structurally related compounds such as 3-keto-1,5-anhydro-D-fructose, D-glucosone and D-xylosone. The enzyme cannot use NADH as cosubstrate. 1,5-anhydro-D-mannitol + NADP(+) = 1,5-anhydro-D-fructose + H(+) + NADPH Optimum pH is 6.5 at 30 degrees Celsius. Monomer. Belongs to the Gfo/Idh/MocA family.