Naruto-verse Dark: Unholy Union

A mysterious man in his sixties dies abruptly, only to find himself in the body of recently deceased boy in a hidden away hovel. Now with a new found life he intends to keep. Making use of skills he picked up in his previous life and the little knowledge he has of this world. He intends to not only survive but also thrive as well as take care of a little sister left behind just like him. A slice in the life of shinobi in a perhaps darker naruto universe.