Sarutobi Toru ultimately did not make a move to satisfy Hatake Sakumo's curiosity.
There was no other reason—he had only just successfully cultivated the Sage Art Black Lightning Chakra Mode and still could not control the strength behind his attacks. He was afraid that a single strike might genuinely injure the two of them.
Speaking of which, the main reason he had managed to cultivate the Sage Art Lightning Release Chakra Mode was Orochimaru from the Parallel World.
Half a year ago, when he had gone to the Parallel World, he discovered that Orochimaru there had found Jugo.
After analyzing Jugo's bloodline, they confirmed that he was a descendant of a Human Sage from a thousand years ago—and an exceptionally rare Ancestral Regression Descendant at that.
Using the hormones extracted from Jugo's body, Sarutobi Toru could finally truly cultivate immortality. After half a year of arduous training, he had become completely immune to the damage Sage Art Chakra inflicted on his body.
However, while sage cultivation could extend one's lifespan, it did not noticeably improve combat strength. Or rather, it would take at least a century of cultivation before any real improvement could be seen. Compared with the rapidly acquired combat power of Chakra, it was truly far behind.
Perhaps that was why the three great Sage Realms had also adopted a cultivation system where Sage Jutsu and Chakra coexisted.
There was no other reason. Though the Chakra system did not extend one's lifespan—or rather, did not do so before one reached a certain level—it was genuinely effective in battle.
Years of cultivation had finally borne fruit. In particular, the development of immortal cultivation techniques had finally freed him from worrying about his lifespan. Given his current condition, living for at least a thousand years would not be a problem,