In the entire ninja world, there are many ninjas who use blood to help perform ninjutsu, but there are very few ninjutsu that must use blood as a medium.

Blood, as a part of the body, is an extremely good chakra conduction material. Generally, the rune materials used to depict seals, barriers, and formations contain more or less blood from animals or even humans. When Shuimu uses spiritualism, because the IQ of jellyfish is too low, in order to strengthen control, he often uses his own blood to strengthen the connection.

Another typical type is ninjutsu that stimulates overdraft of the body, which severely squeezes the blood or other parts of the body. It is common to see secret techniques that burn blood and energy to fight for one's life.

In addition to the above methods, there is also a sacrificial type. The most famous of this type is Hidan of the Akatsuki organization. The blood-sacrificing spell that involves sacrificing one's own or others' blood is an extremely strange and evil curse.

Regarding the principle of summoning, Mizuki didn't know if it had any similarities with this type of sacrifice, but looking at the insect manipulation technique of the Aburame family, it was a secret technique that used one's own chakra as an exchange, using the body as an insect nest in exchange for the insects' help in fighting.

So in general, unless it is a situation like Shuimu where he is the leader and the summoned beast is extremely weak, it is hard to say that the summoned beast will come to help in the battle without any cost.

What's more, high-level summoning beasts are all intelligent species. The best among them, such as the Toad Sage, the Snake Sage and the Slug, are all creatures that stand at the top of the world. Without any demands, how could they possibly intervene in the fight between humans? Even if Kaguya Otsutsuki is resurrected and all humans are enslaved by the Infinite Moon Reading and all turned into White Zetsu, what does this have to do with them? Toads still eat bugs, and snakes still eat frogs. Why bother to predict the child of destiny?

If there is a most famous technique that requires something to be sacrificed, it must be the Shiki Fuujin. Only by sacrificing one's soul can one summon the god of death whose true identity is unknown to launch a soul attack and seal it.

As the name suggests, the summoning technique can be understood as a ninjutsu to communicate with certain beings. Although it is not the same as the Shiki Fuujin, the principle is somewhat understandable. The only thing I don't understand is what exactly did the summoned beast get from humans? Or in other words...

"Did he not get any benefit directly from humans, but indirectly from this world? If so, it is possible, but I can't say for sure without seeing the real contract scroll."

Thinking of this, Shuimu picked up the spiritualism materials again and looked at them for a while, but found nothing.

"It seems that we still need to conduct a thorough investigation and not jump to conclusions."

…

The next morning, Mizuki looked at the fake Jinchūriki who was still recovering from his injuries. His condition was basically stable and he was no longer in danger. In fact, he had to test the violent version of space teleportation in order to escape.

Before he became a fake Jinchūriki, summoning was effective, but now it doesn't work. After careful inspection, it's easy to find the reason, because summoning is a ninjutsu between two individuals, but now the summoning contract identifies that he and the fake Jinchūriki are the same person, so ordinary summoning is ineffective, and at most some means are used to strengthen the sensory connection between the two. If it weren't for this, Mizuki wouldn't have to rush to develop any space ninjutsu, but he didn't expect that real space ninjutsu would be so difficult, which was completely beyond his expectations, so he was very concerned about summoning, a ninjutsu that achieves space transmission. At this time, Mizuki truly realized how powerful the Flying Thunder God Technique, which can develop space ninjutsu based on reverse summoning, is.

In the Konoha Hospital, many injured candidates were receiving treatment there. In fact, Mizuki, who had no mission at the moment, was not disturbed by many people. Among the people coming and going in the ward, occasionally there would be dead people with their faces covered being carried out, and some of them were rescued by Mizuki himself.

When they arrived at the intensive care unit on the top floor, Kakashi was already waiting.

"What's the matter with calling me here, Kakashi?" Mizuki asked after he came in. He looked around and saw that there were still a few Anbu on guard.

"As you can see, Sasuke is seriously injured." Kakashi gestured, "But he will have to take part in the third Chunin Exam in a month. I need to give Sasuke some special training, which is also a form of protection."

"So?" Shui Mu asked in confusion, "You're not here just to show off your teacher-student relationship, are you?"

"Hear me out," Kakashi explained patiently, "It will take a long time to protect and train Sasuke alone, but all three of my students have entered the third exam."

"Oh, I almost forgot to congratulate you, Konoha technician, for your good teaching."

"Ahem, let's not talk about that for now." Kakashi said awkwardly. In fact, apart from some basics, Kakashi did not teach too much to the new Genin. "So my other two students have no one to guide them for the time being. In the third exam, targeted improvement is very necessary, so I asked Ebisu to give Naruto, who has the worst foundation, some remedial lessons."

"Oh." Mizuki understood after hearing this, "You want me to help you train Sakura?"

"Yes, please help."

"You are mistaken." Mizuki refused, "Ebisu is a special jonin who specializes in teaching. It's okay for you to go to him, but why go to me? It's true that you are biased."

"Don't rush to refuse." Kakashi explained, "During the last preparatory exam, Sakura guessed that it was a test for the village, so she asked me who the examiner was."

"So you betrayed me?"

"This can't really be considered a betrayal," Kakashi said, "Sakura herself asked you to come and coach her."

"Oh?" This is strange. "What's the point of looking for me? Her opponent is the strongest Sound Ninja. The gap is too big. Does she have any other ideas?"

"I don't understand girls' minds, but I really can't find anyone suitable to teach Sakura."

"So you're asking me to make up the numbers?"

"Not really. With your strength, Sakura can't learn sealing techniques, barrier techniques, illusion techniques, etc. at the moment. There's not much difference between you teaching her and me teaching her. Other techniques can't improve her strength quickly for now."

"Sealing techniques and illusion techniques barely count, but what's the point of learning barrier techniques? It's better to rest more and conserve your energy. The opponent's sonic attack is too troublesome."

"I'll leave this to you anyway. Sakura, just learn whatever you want to learn. It's up to you."

"Since it comes to this, it's fine, but~" It's okay to do a favor, but if it can be repaid immediately, it is also a good choice.