Yoshitaka Igasaki
He is the Last Ninja and the grandfather of the core five Ninningers and father of Tsumuji Igasaki. He fought against the revived form of Gengetsu Kibaoni, who had returned as a Youkai following his fall and defeat in the Sengoku era. During the climax of their fight, Yoshitaka used 48 Sealing Shuriken to seal Gengetsu Kibaoni and his army. In the present day, he was believed dead, but he was just hiding. He returned to assist his grandchildren in their fight against Youkai Kamaitachi and the rest of the Kibaoni forces. To do so, he gives the Ninningers their Otomo Nin Shuriken to fight fairly with the enlarged Youkai. He then fully appears to the Ninningers after Takaharu talked about assuming his mantle, revealing to them that he was still alive and fairly disgruntled about the assumption of his passing. He can't fight the Kibaoni Army Corps like he used to because of his age, and has to wait for his grandchildren to surpass him as a ninja to become the next Last Ninja.
Tsumuji Igasaki
He is Takaharu and Fuka's father, as well as Yakumo, Nagi, and Kasumi's uncle. He had called the Ninningers to their clan's dojo. His son Takaharu proudly accepted the mantle of Ninninger but the others refused. While on their way to Gengetsu Kibaoni's resting place, he sensed "something off" until Gengetsu was released from his seal. After the Ninningers defeated their first Youkai, he met Yoshitaka whom was taught to be dead. While not a ninja himself, he runs the Ninjutsu Dojo, where the Ninningers train their ninja skills. He is a happy-go-lucky man, though his daughter doesn't find his antics amusing. He is a bit wise, having Takaharu to take a rest while his teammates tried to get on the same level as him.