This is an in-depth treatment in English of Japanese law and practice governing unfair competition. The author analyzes the interaction of the relevant laws - and the case law derived from each - to present a systematic description of how business reputation, trade secrets, well-known marks, and other aspects of business achievement and investment are protected against undue exploitation in Japan. Prohibited acts of unfair competition covered include: misappropriation by confusion or passing-off; misappropriation through breach of trust or fiduciary duty; slavish imitation of distinct product features; trade mark piracy; tortious acts of denigration, libel, and slander; direct interference by, e.g., boycott or bribery; undue exercise of intellectual property rights; and misleading indications on goods and services (e.g., of geographical origin). Several problematic areas - in particular, the obstacles to effective enforcement, and the lack of adequate protection for consumers against acts of unfair competition - are given particular emphasis.