Junghuhnia japonica is a species of poroid crust fungus in the family Steccherinaceae.

The type specimen was collected in Ōkuchi, Japan, growing on a rotting log of Castanopsis.

One type is thick walled and heavily encrusted, measuring 40–70 by 9–15 μm.

[1] The fungus was described as new to science in 1999 by mycologists Maria Núñez & Leif Ryvarden.

J. japonica is similar in morphology to J. luteoalba but that species has narrower spores and lacks gloeocystidia.