How could Mitsuki attain Sage Mode without training?


During the final test, Mitsuki was subconciously able to enter into Sage Mode
without prior training at any of the Great Sage Lands. [![enter image
description
here](https://i.stack.imgur.com/hjBJu.png)](https://i.stack.imgur.com/hjBJu.png)
How was this possible?

