The Yin Seal, How Sakura will use it.

[Little My]

. Although I still think she might be able to do the same or something similar to Tsunade, I don't think it will be an improved or superior version.

Well if we use Naruto and Sasuke as a precedent then Sakura should develop unique techniques to go along with the ones she leartn from Tsunade. I do hope that Kishi will reveal a new technique for her but as you mentioned its not very likely to Kishi developing females means they'll end up being used as protective meat shields.

 

[Honord Sage]

Mito Uzumaki was the first to have one She showed Tsunade How to use it, Tsunade tried to teach it to Shine and fail, now She showed Sakura how to use an Uzumaki storing seal.

 

[aindafeliz]

Mito Uzumaki was the first to have one She showed Tsunade How to use it, Tsunade tried to teach it to Shine and fail, now She showed Sakura how to use an Uzumaki storing seal.

Seeing as Mito was still alive when Kushina was young, I too think that Mito was the one who taught Tsunade the seal, as Tsunade is older than Kushina.