After Hashirama was beaten to the extent that he may have lost another 6 months off his life, they began their trip to the Land of Whirlpools.
The trip was mostly unexciteful other than Tsunade perfecting her kanji after only two days of practice.
While she had already learned its basics with her learning medical ninjutsu, perfecting it is something that usually takes even geniuses a few weeks to do.
So while Mito had given that goal, she didn't actually plan for her to succeed in doing it, however it showed her the terrifying talent that Tobirama always talked about.
So on the 2nd day of the trip, when they stopped to eat dinner for the day, Mito brought out a basic Fuinjutsu scroll from a Storage Seal while also preparing to teach Tsunade the basics of sealing.
The two walked to an open area before Mito began to be speaking "Fuinjutsu is both one of the most unused and most terrifying forms of Jutsu that shinobi often encounter. It is unused due to the vast amount of knowledge that is required to use it that can exceed even Medical Ninjustu. It is composed of Jutsu that uses Kanji as a conduit to do certain things such as sealing different things from objects to ninjutsu to even people. It can also be used as the basis to summon Otherworldly Beings. It can be used to impose things such as increased gravity or to form barriers. Now how do you view Fuinjutsu Tsuna?"
Tsunade thought about the question first 'Fuinjutsu was one of the most under used in the Anime. It wasn't shown much, but when it was it was either able to imprison Tailed Beast, teleport using Space-Time seals, or seal Kaguya. Soo..'
Tsunade then answered by saying "I feel that fuinjutsu gives you the ability to seal anything as well as perform innovative actions."
Mito smiled at the answer before saying "That could be an interpretation of it, either way we will start training you in seals, starting with a storage seal. The storage seal is created by using the Enclosing Technique, which you form by using these kanji."
Mito then showcased to Tsunade the kanji she would need to do the technique as well as the ways it could be used such as storing resources for long term missions or ninjutsu for combat related missions.
Tsunade showcased her Uzumaki Bloodline by being able to do it on the first try, however she only suceeded with a small tree branch.
Mito told her that the size and amount you can seal depends upon what your trying to seal, the preciseness of the kanji, and the amount of chakra being put into the scroll which requires delicate control over chakra that could rival Medical Ninjutsu.
However that proved to not be a problem for Tsunade as she gained more and more mastery over the Enclosure Technique.
She finally perfected it to an extent Mito would deem acceptable, when she was able to seal an entire boulder into a single scroll.
The night sky shown on Mito as she then smiled proudly as she told Tsunade "It is incredible to master any Fuinjutsu technique in a few hours, even I would not be able to do such a thing at your age even with the easiest of them. I'll teach you a few more before we make it to the village. I didn't think your talent for seals was so terrifying. Now let's return to the carriage before your grandfather makes the decision to gamble with a tree."
On their way to the carriage Tsunade thought about the question she was asked earlier before asking Mito "How do you view Fuinjutsu, Grandma?"
Mito seemed surprised by the question before answering "I feel that Fuinjutsu is the conduit in which we manipulate the world around us. It makes the impossible possible and makes people able to reach the unreachable. The only limit to Fuinjutsu is your knowledge and understanding of it."
Tsunade seemed to be thinking about the answer while the two made their way to the carriage under the night sky.