Of all the realist RPG books available, this sheds the most light on the Yakuza, the Japanese Mafia, the most dominant group in the underworld of Japan. It brilliantly describes their history, organization, personality types and activities. As a case study, topic for debate or writer's resource, this will answer every possible question about the Yakuza. The size of the book is perfect, too, not too long, not too short.