Malakas came ashore mid-afternoon on 19 September, and hit the 30MW Kimotsuki project, in the Kagoshima prefecture in southern Kyushu, owned by Eurus Energy.
Four turbine blades were damaged, with buckling seen in two of the turbines, the company said. The damaged was discovered on 20 September, and the wind farm has been taken offline pending an investigation into the extent of the damage.
Kimotsuki comprises 15 2MW J82 turbines produced by Japan Steel Works.
Elsewhere in the affected area, the Minami-Oosumi wind farm owned by J-Power saw damage to nacelle covers, according to Yoshinori Ueda of the Japan Wind Power Association.
J-Power acquired an 80% interest in the project with 20 Nordex 1.3 MW turbine-based in 2009, company records reveal.
Malakas is described as equivalent to a category three hurricane on the five-point Saffir-Simpson scale, with winds of up to 185kph.