Hitoyol A (1), an unprecedented norsesquiterpenoid with an exo-tricyclo[5.2.1.02,6]decane skeleton, was isolated from the culture broth of Basidiomycete Coprinopsis cinerea along with a novel skeletal hitoyol B (2) containing 4-cyclopentene-1,3-dione. Their structures and absolute configurations were analyzed by single-crystal X-ray diffraction and electronic circular dichroism spectroscopic methods. Compound 1 is possibly biosynthesized through decarboxylation-induced cyclization of lagopodin B, a known cuparene-type sesquiterpenoid. Compound 2 showed weak antimalarial activity with an IC50 of 59 μM.