I use the ninja world to help me cultivate immortality

Naraku is an ordinary member of the Root organization. The only bright spot may be that he has a beautiful "partner" named Yakushi Nono.
The above is Naraku's resume before he was 18 years old.
After he turned 18... he didn't eat beef!
After awakening his wisdom and discovering his companion immortal fate, Naraku has since changed from a ninja to a full-time immortal cultivator.