A novel C35-terpene, designated as cryptotrione (1), with an unprecedented skeleton possessing an abietane diterpene with a unique bicyclic sesquiterpene, is identified from the bark of Cryptomeria japonica. The carbon skeleton of 1 represents a new structural entity, and this is an intriguing addition to the structurally diverse diterpene-sesquiterpene class. A unique biosynthetic pathway is proposed to support the production of this phytocompound. Notably, 1 exhibits anticancer activity with an IC50 value of 6.44 ± 2.23 μM.