Under normal circumstances, Kabuto should have been exceptionally well suited to Ryūchi Cave's Sage Mode. But because of Uchiha Chisen's influence, Kabuto had never received enough tempering under Orochimaru. Even his trip to Ryūchi Cave had been against his will.
On top of that, Kabuto was fixated on inheriting Orochimaru's legacy, which naturally made it difficult for him to sense natural energy and successfully enter Sage Mode.
"No, you are the most suitable successor to Ryūchi Cave. In some respects, you are even better suited than that fellow Orochimaru!"
To Kabuto's frustration, however, the White Snake Sage rejected his request outright.
As a sage of one of the Three Great Sage Lands, the White Snake Sage also had a limited ability to foresee the future. In the future she had foreseen, she had seen Kabuto successfully master Ryūchi Cave's Sage Mode. That was why she had brought him back.
"I'm better suited than Lord Orochimaru to be Ryūchi Cave's successor?"
Kabuto did not really believe the white snake's nonsense, but there was little he could do. With a snake's jaws looming over him, he had no choice but to bow his head. Even though he longed for Orochimaru's legacy, he could only remain in Ryūchi Cave for now.
What Kabuto did not know was that staying in Ryūchi Cave might not actually be a bad thing.
Meanwhile, after waiting so long without seeing any reinforcements from Konoha, Uchiha Chisen had begun selecting ninja in Kirigakure to form the beginnings of a military police force in the Land of Water.
"Are you sure it's a good idea to make me captain of the Land of Water Military Police Force?"
"I was one of the Seven Ninja Swordsmen of the Mist, you know. Then I became a rogue ninja, joined the Akatsuki