Board Thread:Naruto Discussions/@comment-1512913-20180923130046/@comment-2120712-20180927171256

My speculation on the Yin Seal is that given Yin & Yang being the counterbalance of each other, The Yin seal acts as container for Tsundade's store up Yang chakra that she uses for Creation Rebirth and related jutsu. The Yin seal is not a medical jutsu, but a method to turn on and off an actual medical jutsu. The problem is that the databooks didn't give Tsu Yin release but Sakura uses the same tech and was given Yin release. Hopefully in the Boruto anime she will use a genjutsu or something, or maybe some exposition by Sakura or Tsu herself about what is involved in setting up Creation Rebirth.