Board Thread:Theories and Speculation/@comment-25093611-20160821131910/@comment-734582-20160823085744

Namikazenaruto9 wrote: i still don't know what one could gain by slug's SM...(which is more like a speculation by the way) It's not really a speculation since the Jin No Sho calls Shikkotsu forest one of the three unexplored sage regions.

As to "soft vs hard" i don't really see a point there. Orochimaru and kabuto extensively experimented upon themselves for their benefit.