On the fourth day after Minato left.
Mu Yue had originally been scheduled to train the Anbu that day, but he took a day off from Hiruzen Sarutobi to teach Kushina the Rasengan.
Mu Yue had left himself plenty of flexibility when planning the early stages of Anbu training, so taking a few days off would not affect his teaching progress.
Before the official training began, Mu Yue first asked Kushina about her current progress.
"Something like this." Kushina held out her right hand and gathered a large amount of Chakra in her palm.
As more and more Chakra accumulated in Kushina's hand, a ball of pure Chakra gradually formed above her palm.
"It doesn't have much power yet." Kushina slammed the Rasengan toward a nearby tree.
Bang!
The instant the Chakra ball touched the tree, wood chips exploded outward. In the next moment, a shallow spherical crater appeared in the trunk.
"Not bad already. Back then, Minato and I spent several months getting to this stage." Mu Yue nodded.
Minato had only just completed the Rasengan's development under Mu Yue's guidance and had yet to organize and break down its training process. For Kushina to reach this level in such a short time was already quite good.
"Hehe, of course. I'm a genius!" Kushina readily accepted Mu Yue's praise.
Of course, although she said she was impressive, Kushina did not lose herself in Mu Yue's praise.
As a ninja, and a relatively strong one at that, Kushina understood that practicing a Ninjutsu and developing one were two different matters.
"Next, you need to increase your Chakra output for the Rasengan, then compress the Chakra to boost its power." Mu Yue began the formal lesson.
As he spoke, Mu Yue held out his palm. A Chakra ball rapidly expanded above