The pirates sat and forgot, and they really believed the nine truths and one lie.

Chopper gradually liked the feeling of taking drugs and learning. Under the stimulation of the blue ball, the unused areas of the brain tissue began to open up functions for their owner.

The advantage is that Chopper can study without distraction, but the disadvantage is that once the effect of the drug wears off, his brain's thinking ability will immediately become dull and he will return to the mode of an ordinary person.

The first blue ball supported Chopper's study for twenty minutes, and the second blue ball shortened the effect time by half, forcing him to exit the brain strengthening stage after ten minutes.

When Chopper picked up the third Rumble Ball, he suddenly hesitated, realizing the risk of doing so. "If I eat another one, I might turn into a monster, lose control of my mind, and hurt them."

Putting down the Rumble Ball in his hand, Chopper felt like he had returned to his stupid self. The books on medical ninjutsu, which he could understand just now, became incomprehensible in the blink of an eye, and he was unable to comprehend the profound content.

After eating two blue balls in a row to stimulate his brain, Chopper has already felt the side effects and feels dizzy, which may be due to insufficient nutrition.

The brain was forced to work at high load, and the nutrients originally provided by the body to the brain had been consumed. Shortly after finishing dinner, Chopper felt hunger signals in his abdomen.

The brain is a high-energy-consuming organ in the human body. Chopper's continuous use of brain enhancement not only overdraws his physical strength, but also makes him mentally exhausted. Chopper wants to sleep very much.

In the end, in order not to cause trouble to the two women beside him, Chopper did not choose to eat the third Rumble Ball. He fell drowsily on the bed, and fainted from being too tired.

The next morning, when Kaya came to call Chopper to eat, she found her senior brother sleeping on a book without even a blanket covering him.

Keya woke up her senior brother Chopper and got a few hours of sleep. Chopper's brain recovered slightly, and he followed behind his junior sister, floating on his feet, and had breakfast with his mentor.

During the meal, Tsunade discovered a small problem. She clearly noticed that Chopper's head seemed to be bigger. Kaya didn't notice it at first, but then she realized that there was always a sense of incongruity when meeting Senior Brother Chopper today.

Chopper is an honest boy. There is no such thing as lying in his life. He tells everything that happened last night in detail. There is always a price to pay for taking drugs to study.

"Let me see the Rumble Ball you've been practicing recently. Is there something wrong with it?" Teacher Tsunade asked for the Rumble Ball, and Chopper obediently handed it over with both hands.

Tsunade held the Rumble Ball in her palm, her palm glowing slightly, and analyzed the medicine used in the Rumble Ball, "The formula is different from last time. You have privately improved the Rumble Ball. The efficacy is more than ten times stronger than last time."

Chopper used the pharmacology knowledge he learned from Tsunade these days to add some powerful ingredients to the Rumble Ball to enhance its effect.

Rumble Balls are the foundation of Chopper's life. A deer ate an ordinary Human-Human Fruit and had to take a shortcut to become stronger. Chopper didn't want to be just a pet, he wanted to become stronger to help Luffy and help the Straw Hat Pirates defeat powerful enemies.

"The effect of the medicine is indeed stronger than before. My body is still adapting, but the side effects are very severe in the early stages." Chopper's voice became smaller and smaller, like a child who had done something wrong next to his mother, not daring to look Tsunade in the eye.

Tsunade cursed in her heart, "Silly boy, why didn't you tell the teacher in advance that you wanted to face danger alone? Did you treat the teacher as an outsider?"

"Come here and let me touch your head. I think the side effects are more serious than I thought." As soon as he finished speaking, Chopper sat obediently next to Tsunade.

Tsunade touched Chopper's head and determined that its bones were protruding. She even used medical ninjutsu to sense the changes in her eldest disciple's skull, and it was exactly as the strange doctor had expected.

"Chopper, you can't take this medicine from now on. I just touched your bones and found that your skull and brain have grown. If you continue to use the Rumble Ball, your head will only get bigger and bigger." Tsunade didn't want her apprentice to turn into a big-headed doll.

There is a fatal flaw in becoming a big-headed doll. The brain tissue will grow larger and proliferate, absorbing more nutrients from the body. Now Chopper's small body can withstand it, but in the future there may be a problem of not being able to supply the nutrients the brain needs on a daily basis.

The brain is more noble than other organs. Reducing the nutrient supply is tantamount to seeking death. It will leave obvious sequelae, and you may even become a fool when you wake up the next day.

Chopper didn't expect the situation to be so serious. The explosive stuff he added to the Rambo Ball was more like a deadly poison to him at this stage.

"But without the Rumble Ball, the Animal System can only provide three forms of transformation, and my strength will only be weaker. I don't want to be just a doctor in the back." Chopper still wants to fight side by side with Luffy one day, and doesn't want to hide behind his companions and be the one who is protected.

Chopper's pleading look made Tsunade feel conflicted. She actually had a way to help her eldest disciple.

Tsunade patted Chopper's little head and said, "You little thing, you always cause trouble for your teacher. If you don't want to give up the Rumble Ball, you must strengthen your body, let your brain and body progress together, and reduce the gap."

The method given by the strange doctor is very simple. Chopper can take the Rumble Ball in front of Tsunade and combine it with a practice method called Senjutsu to consume the excess medicinal power of the Rumble Ball.

Senjutsu is a more advanced form of energy utilization than medical ninjutsu. It increases the absorption of natural energy from the outside world and stores it in the body, allowing it to attack and defend at any time.

The magic that Tsunade learned was passed down from her ancestors. By the generation of the strange doctor, she was the only one left in the family. If the magic was not passed on to outsiders, there was a high probability that it would be lost.

After all, Tsunade will not get married for the time being, and she has no brothers or sisters and no children. If she does not pass on the magic skills to her two apprentices, the secret skills passed down by her ancestors can only be taken into the coffin by a woman.

"Senjutsu"?! Chopper hadn't expected such a surprise to be waiting for him, but he was a little worried. He hadn't mastered medical ninjutsu yet, so it would be too hasty to skip the simple ones and learn the more difficult senjutsu.

"From the records of my ancestors, immortal arts were not originally invented by humans. It was creatures more powerful than humans who summed up a set of rules suitable for themselves based on their understanding of nature." Tsunade actually wanted to say that immortal arts might be more suitable for animals. The immortal arts learned by humans have all been modified and have great limitations.

Chopper was originally just a blue-nosed reindeer. He had no noble bloodline and no powerful relatives. He was just an animal lower than humans.

It is precisely these lower animals that are integrated into nature that are closer to nature than higher animals like humans. This can be considered a blessing in disguise.

For the time being, Kaya is not very interested in the magic that her teacher mentioned. She has just started learning medical ninjutsu. She needs to master it before considering the magic.

The girl herself does not have much fighting desire. She considers herself to be a rear support unit. She learns medical ninjutsu and has the ability to protect herself. Fighting for strength or going to the battlefield is not suitable for Kaya.

Chopper didn't think much about it and agreed to his teacher's suggestion. He wanted to learn powerful magic and didn't want to be a pet worth only 50 berries!