Life as a Leaf Shinobi

After dying, Allen found himself in the world of Naruto. But the Shinobi world is in danger. Every ten years the members of the Otsutsuki Clan attack the Shinobi world and kill a large number of strong ninjas. It's been 29 years since the first Otsutsuki Clan attack on the Shinobi world. Now another attack is about to happen. Will Allen be able to survive this attack, and achieve his dream of becoming the strongest man in the world?