15 Tsunade

Shikkotsu Forest.

After telling his schedule to the outside world, Yuki would take some time to come here every day to learn immortal arts from the living slugs.

The so-called immortal arts referred to the power of fusion by absorbing the natural energy of the outside world into the body and combining it with the balance of body energy and spiritual energy. After that, this kind of power would be far more powerful than that of ordinary chakra.

Besides balancing the three energies in the body, the key to cultivating immortal arts was how to absorb the external natural energy.

In the beginning, Mount Myoboku, one of the three great holy lands, was cultivated using the toad oil on his body to feel and absorb natural energy.

The method of the Shikkotsu forest was different. The transparent mucus secreted from the mouths of the little slugs on the outside contained rich natural energy.

As for Yuki's immortal arts cultivation, he smeared this transparent mucus on his body and directly absorbed the natural energy.

In terms of efficiency, he was much faster than Mount Myoboku.

However, this kind of cultivation method also had a very serious shortcoming.

That was, the transparent mucus of the slug itself also had a strong corrosive effect.

Once smeared on the skin, while the cultivator absorbed natural energy, they also had to endure the corrosion of the body.

It wasn't easy to persist unless they mastered medical ninjutsu or had extremely strong self-healing abilities.

However, the former would increase chakra consumption, which was also the time to absorb natural energy. This further tested the ability of the cultivator to balance the three energies in his body.

As for the latter, even though the Senju Clan or Uzumaki Clan, which was famous for their physique, had an excellent self-healing ability, it was still not enough when facing the corrosion from the slug.