Tobi_444
It seems that in addition to being robotic, the MC is asexual, not that there are any relevant characters for romantic interest for this eunuch MC.
I agree that Tsunade is one of the best female characters in the Naruto work and yes she is very little used, I know that after becoming Shinobi they are adults and yet in the work there is no couple with a significant age difference, yes it would be very good if the MC wasn't almost completely apathetic and the last few episodes see a slight improvement in that but it probably has more to do with the other characters than with MC, not even the original Tobirama was that apathetic the MC almost seems like Danzo's wet dream, apathetic, emotionless and robotic who would fall in love with a character like that, Tsunade seems to have a very specific lover profile and even the people closest to her follow the same idealistic and emotional profile but of course this is fanfic it doesn't need to follow the personality pattern of the work original, one of the biggest problems is that the MC is very disconnected from Konoha and he has no real goal other than to survive and I don't doubt that the main events will follow the canon, perhaps a romance with Tsunade of the connection that the MC lacks .
Rk6T:I would agree with you if it wasn't for the fact that MC seem to be more mature than her not to mention his hight makes him look like an adult or 18 year old at least and that he is still getting taller. Also this is the shinobi world, they are considered adults as soon as they become genin with the license to kill. It wouldn't be strange in the slightest. Now tsunade would defo not take him serious if he behaved his physical age but MC is an adult in mind already. So it would make the most sense. Btw Tsunade is almost never the main female lead so this would be a breath of fresh air, specially considering she is one of the best female characters in the series.