Shingen was kashira (leader) of the Neko Ninja and was a master of his craft. He first appeared in Vol.1 #12 where he was on a mission to steal a Muramasa sword from Lord Noriyuki. His skill was so refined that when he was speared in his hiding place by Tomoe Ame who sensed an intruder, he still escaped detection by refraining from crying out in pain at the wound and wiping the spearhead clean as Tomoe withdrew to remove evidence. However after getting the sword, he was found by Miyamoto Usagi who followed him and tricked the ninja out of the sword while keeping his attention while the sword was making its way back to the city.
In the story, "The Dragon Bellow Conspiracy," Shingen was assigned to a new mission to investigate a daimyo Lord Tamakuro who was plotting a coup against the shogun with a large stock of firearms. However, when the daimyo learned of the Neko Ninja's attention, he ordered a village populated by the clan destroyed. Later, Usagi discovered the carnage and moved the bodies as an act of respect. However, Shingen saw Usagi doing this and misconstrued it as the samurai killed the village himself. He attacked Usagi in revenge, but was defeated and thought to be killed when he actually escaped.
Later, Shingen learned the truth and gained Usagi's assistance to strike against Tamakuro. To do this, Shingen revealed that the ninja clan was far more numerous than even Lord Hikiji suspected. With these numbers, explosive weapons and allies like Murakami Gennosuke, Tomoe Ame and Zato-Ino, the Neko Ninja assaulted Tamakuro's castle. Although the Neko suffered heavy casualties, Shingen was able to penetrate the inner defenses to strike the traitorous lord although he was mortally wounded in the attempt. With the last of his strength, Shingen sacrificed himself to kill the enemy by using his fire strikers to ignite the black powder in the room. This caused a massive explosion that killed the lord and his forces.
His sister, Chizu, eventually assumed the leadership of the weakened clan.