Naruto: My Undying Self Becomes a Master of Forbidden Arts

In the Naruto world, Hinata and Tsunade are the female protagonists you can get for free. Hinata will remember you for life if you save her. Tsunade has hemophobia; with alcohol, gambling, and blood stimulation, you can easily win her over.

The main character hasn't been seen in the last few chapters; it's unclear who's the protagonist. Has Itachi been changed to the main character?

If the protagonist is immortal, they can inject Hashirama's or Kimimaro's cells to integrate Yin and Yang power, upgrading both their eyes and body. The Caged Bird Seal can be broken using Yin-Yang power (Yin-Yang Release) or by powerful Yin power allowing the soul to break free.

Not bad, that's feasible. Let's see if combining the Shikotsumyaku (Corpse Bone Pulse) and Hashirama's cells can awaken the Sage Body in the protagonist. Is the female lead single? That Uchiha?

The protagonist can defeat Kisame right from the start? How did he acquire such strength? So what did you do in the Land of Water? What was the purpose of all those things you did?

You could try cloning your own genes into some soulless clones, then implant your own soul into them using Orochimaru's Heaven and Earth Seal or similar soul-splitting techniques. Next, add new blood to these clones, and after mastering the technique, exchange your original chakra, discard your physical body, and then fuse your souls together.

Does Chiyo possess a technique that can revive an object?

Hidan's immortality makes him a perfect experimental subject. He can be used as research material for sustainable studies. Since he can't be killed, experiments can be conducted on him continuously.

I recommend the Naruto fanfiction "Becoming the Tsuchikage in the Naruto World," which has no system.