Gennō

was a ninja of Kagerō Village, a village that had frequently clashed with Konohagakure in the past.

Background
When his village was wiped out, Gennō was the only survivor. Decades later, with his life failing, Gennō decided to resurface his last mission from his village. He began by infiltrating Konoha as a carpenter. After successfully placing himself within the village, he stole the blueprints of the fort structure around Konohagakure to refine his leftover traps from his last infiltration. After the village was left preoccupied with threats of an impending invasion by a neighboring country, it was left to the Konoha 11 to stop Gennō.

Abilities
Despite his elderly age, Gennō was still a formidable and famous ninja. His greatest trait was his intelligence, which was great enough to outsmart an entire squadron of ANBU. Like Shikamaru, Gennō was adept at perceiving everything around him and formulating well-thought-out plans several steps ahead of his opponent that could also involve misdirections, as well as quickly altering his plans should the situation change. His intellect best served him in his actions as a trap expert, which earned him the the nickname "The Trap Master".

Since Gennō's style for traps revolved around infiltration of an enemy's territory and stealthily laying explosives, he proved himself to be a very capable actor. According to Shikamaru, Gennō's talent for infiltration, whether hiding in the shadows or blending into the environment and disguising his true objective, deserved legendary status.

Gennō was shown to be very crafty, as well as skilled in battle, utilizing several expert level combinations of taijutsu, ninjutsu and genjutsu. He would regularly use his trap expertise to make his opponents more hesitant to approach him by rigging himself with poison gases. In terms of taijutsu, he was able to keep up with Rock Lee, and presumably only lost because of his failing health.

Trap Master arc
Although Gennō was at first only interested in destroying the village, he came to appreciate Naruto Uzumaki and the young generation's determination as they managed to find and safely remove his bomb. He then decided to use his trap-making skills to give them an interesting hunt. He amazed the young ninja by how skillfully he faked his death and how he successfully planted exploding tags all throughout the village in a chain-effect. After Sakura Haruno, Hinata Hyūga and Ino Yamanaka discovered that Gennō was still alive, Gennō decided to move into the final phase of his mission. Gennō then had his bird drop all of the blueprints all over the village. Whilst everyone tried to make sense of them all, Gennō planted more exploding tags in and on the face of the Hokage Mountain.

Eventually, Naruto encountered Gennō at the Hokage Mountain where he then revealed everything, including his plans to blow up the mountain to bury Konohagakure. With his plans finally revealed, he took on the Konoha Genin. He managed to dodge Kiba Inuzuka and Akamaru's combination attack, and used a trick to escape Shino Aburame's insect attack. After using a genjutsu, Gennō summoned a giant bird. When Ino entered his mind, she felt pain so extreme that she left it immediately.

Rock Lee then moved in to subdue Gennō, but he managed to match Lee's taijutsu. Gennō then finally revealed the final part of his plan, as he had placed exploding tags in the Third Hokage's face as a trigger for the explosion. After Naruto and Chōji Akimichi defeated the bird, Gennō could no longer push his ailing body any further, and he passed away from old injuries that had never healed. When Shikamaru explained to the Hokage what had happened, he said that Gennō had intended to blow up the village when he first arrived. However, after Gennō had met Naruto, he had decided to not blow up the village. Instead, he turned his plan into a treasure hunt, like he had done with his own son, since Naruto had reminded him of his son.