In Naruto as Ten Tail

Tsukimi looked at Tsunade coldly, hearing her questions. Her words could paint a target on his back.
"What are you saying Tsunade? If these practiced Medical Ninjas cannot use your techniques. How can he do that?"
Dan asked with a frown on his face. His Words made Tsunade realize that she had been too hasty in speaking.
Seeing the cold look on Tsukimi's face she bit her lips. Thinking quick on her feet she thought of an excuse.
"They may be Medical experts but these three had high chakra control for a long time and because of that I had taught them some of the basic healing jutsus and control techniques when they were living with us for the past two years."
Hearing Tsunade's words, Tsukimi's frown turned into an amused look. He was not really angry at her but he wanted to show her that there are lines she should not cross.
He may not mind her aggressive behavior but it did not mean that he had to put up with it.
"Did you not tell the Hokage-sama about this?" Dan was shocked to hear that Tsunade had been personally training these kids. He had never heard about her taking an apprentice under her wing. Do couldn't help but be skeptical about it.
"Nope! The old man does not know because they are not my official students. I had just given them pointers when I was free, the rest they learned by themselves."
Tsunade shrugged her shoulders saying that, after she started finding the true nature of her teacher she unconsciously distanced herself from the people under or near him too.
This was also one of the reasons she did not get too close to Dan, who was directly under the Hokage.
"Sigh~, What will you do even though they have good chakra control, will they be able to learn your technique in a short time?"
Sighing Dan tried to persuade Tsunade, to him training the kids was nothing but a waste of time. They did not have the time to waste when the lives of the Ninja's were on the line.

Tsunade did not seem fazed by his words but looked at the boy in front of her silently waiting for his answer. Tsukimi understood what she wanted to know and sighed.
He thought for a file before extending his hands and forming a few hand seals.
"Cloning Technique?"
Dan mumbled with a puzzled expression but his eyes widened when he noticed something.
"Shadow clone technique?!"
With a small puff of smoke that was made using an illusion by Tsukimi, tens of shadow clones appeared in front of them.
Dan looked at him with mouth wide open. Not only did boy in front of him create 19 clones but the small puff of smoke he made also suggested how good his chakra control was.
Whenever a Ninja performs a Jutsu they leave a puff of smoke which is usually the excess chakra they waste while performing the technique.
The Ninja who produces a low amount of smokes while performing a Jutsu means that they have a good grasp of the Jutsu and they have good chakra control.
"This was the technique Ingave him because of the good amount of chakra he has." Tsunade spoke with a slight smirk on her face. She noticed that the chakra control the boy had was almost around the level of hers.
She was truly astonished seeing his control and really wanted to take him as a student for herself. As for the shadow clone technique, it was Tsukimi who asked her to teach him in exchange for a fight she demanded from him.
Being the gambler she readily agreed but this was not something she wanted to tell others. She just used an excuse as a cover for her habits.
Tsukimi almost snorted after hearing her response, Tsunade seeing the ridiculous look in his eyes blushed slightly before she glared at him.
Rolling his eyes, Tsukimi disperse the Jutsu.
*Poof!*
With puffs of smoke the rest of the clones vanished. Dan also came out of his shock and looked at the boy with a pondering look.
"This should be enough for me to 'waste' my time on him. Besides, This is what I want to do and I will shoulder the responsibility for my actions too." Tsunade declared, casting a short look at the man beside her.
"Boy come with me, I will teach you this technique and you will practice it today with your clones and I want you to learn this technique as soon as possible. This will be a A rank mission from me to you. Each person you cure will be counted as completing an S rank mission."
Tsunade ordered and lead the trio back to her workplace.
Dan did not follow them but he left for his own duties, he wanted to spend time with Tsunade but he did not have the Luxury to do so as there were many things he had to do for his own missions.
.
.
.
Back in the workshop, Tsunade looked at Tsukimi with an annoyed look on her face.
"Now brat, tell me how long would it take you to use this technique?" She knew Tsukimi was more capable than he had just shown himself to be.
She did not like these turnaround ways which is why she was getting annoyed.
"Hmm~ who knows. Why don't we bet?" Tsukimi replied with a smirk on his face.
Seeing the smirk, Tsunade snorted and replied in anger.
"Brat, do you think I will fall for that again? I will bet with someone else knowing I might lose but I won't ever bet with you!"
Tsunade pointed her finger at his chest as she spoke. Hearing her words, Tsukimi chuckled and did not say anything.
Without making any hand seals, he created several clones of himself and seeing those clones Tsunade eyes went wide.
If she could ignore the fact that there were almost 100 shadow clones in front of her, she was shocked that Tsukimi did not even need hand seals to perform this technique.
'His Chakra control is above Me!'