I just recently rewatched the Zoro vs Daz Bones fight and saw this particularly interesting flashback and this theory just hit me.
Zoro gets a flashback of his Sensei telling him that there are swordsmen in this world who can cut nothing.
Then it shows Zoro in present day saying to himself “ To be able to cut nothing, does that mean to know the breath of things?”.
He then proceeds to defeat Daz Bones who asks Zoro if he’s going to cut Diamond next and Zoro says that would be a waste.
This is what sparked all those theories that Shiryu of the Rain would somehow get Jozu’s diamond fruit and fight Zoro in the future.
Now you know that Shiryu got Absalom’s Suke Suke no Mi and can now turn invisible.
Most people were complaining why Oda gave Shiryu such a weak devil fruit, in fact even if invisible he can still be discovered by anyone with Observation Haki.
Now, looking at that flashback with Zoro’s sensei, I think I know why Oda decided to give Shiryu that particular devil fruit. The Suke Suke no Mi gives him the ability to turn himself and anything he touches invisible, and its Awakening has to be I think to be able to turn him into nothingness.
I know this is a bit weird but I believe the next level of invisibility is to become nothing.
Zoro will not be able to sense him at all even with Observation Haki. Shiryu will become nothing itself and that will be Zoro’s true test which is to be able to cut nothing just like his sensei said in that flashback way back in Alabasta.
I’m telling you that this has to be why Oda gave Shiryu the invisible fruit in particular out of anything else. It will be a very tough fight for Zoro but he has to pull through somehow.
*Theory by ram_sauce