I dont understand how you are linking suren caves with shikkotsurinslug sage mode is not there and as mentioned inYou must be registered for see linksandYou must be registered for see linksthe only sage mode are
1. Great Toad Sage - Mount Myōboku
2. White Snake Sage -Ryūchi Cave
3. Sage king of apes -Shikkotsurin (Suren caves)
And it would make more sense some type of slug SM existing since toad and snake (dragon) SM exist