Set in present day Tokyo, the story revolves around a rather incumbent fellow by the name of Harusuke Shiraishi. At first, Harusuke appears to be like any other young guy in his 30′s but, it’s soon revealed that he is in fact the 27th generation successor to the long forgotten Hikage-ryu school of Ninjutsu.

Before long, we learn that the Hikage-ryu was once a very well respected Ninja clan throughout Japan but it’s name was thrown to the dirt when it’s rival clans, The Iga and Koga, agreed to join forces and enlist the help of Demons to overthrow the hapless Hikage-ryu. When the barrier between the Human and Demon world was destroyed, the then current Hikage-ryu grandmaster and 3rd generation successor of the school, Sounsai Shiraishi laid his life on the line to protect the Human world by fighting the formidable Demon lord in a battle that would last 5 days and 5 nights. Despite his best efforts, Sounsai eventually fell prey to the Demon lord and was torn from limb to limb. From that day on, feeling responsible for allowing the Demons to invade the human realm, the Hikage-ryu disbanded and went into hiding out of shame…

Fast forward several hundred years to present day Tokyo and the now current successor, (27th generation) Harusuke Shiraishi, lives in a Love hotel with his elderly Aunt who herself is the lone remaining female Hikage-ryu ninja. Of course, being a ninja alone hardly pays the bills so it’s down to these two to make a quick buck wherever they can. The solution? A detective agency! Well, as you’d expect with a family lineage running as far back as the Hikage-ryu, their detective work doesn’t involve seeking out human targets, rather their field of expertise is called upon by victims of unexplainable phenomena. In other words, Demons!

(Source: tentaclelounge.wordpress)