#7 in the Lawson Vampire series.
Lawson heads to Japan to get some rest as well as take in advanced ninja training. What he finds as soon as he gets there is a turf war inside the Yakuza brought about by someone called the Kensei. That individual is making a lot of money dealing in organ trafficking and using it to create an army of vampire-human hybrids. Helping Lawson is the former KGB-assassin named Talya.