Apparently there are more books in this series in Japanese than just Shinjuku Shark and The Poison Ape, but I can see why only two were translated into English. There was no mystery involved in this installment featuring a highly trained Taiwanese assassin for hire out wreaking havoc in the Japanese underworld as he seeks personal revenge. The story seemed a bit flat and predictable, but it might still be an easy and worthwhile read for Japanophiles.