The Hyper-CBD Challenge: A Breeding Strategy for Japan's Regulatory–Biological Mismatch

This paper identifies a fundamental contradiction in Japan's cannabis regulations and proposes a breeding strategy for "Hyper-CBD cultivars" as a scientific response. It examines the three-tiered regulatory barrier — cultivation licensing, extraction authorization, and residual THC thresholds — and the biological barrier posed by the side-reaction activity of CBDA synthase, which generates trace THC even in THCAS-null cultivars. A two-stage molecular breeding approach — THCAS inactivation followed by CBDAS specificity engineering — is proposed, with a GACP-licensed farm in Phayao, northern Thailand, positioned as a candidate pilot site.