At first, Tsuchima really had been Obito's will.
Two months earlier, just before Madara left for Mount Myōboku, he and Black Zetsu had parted ways.
That was when Black Zetsu had usurped Tsuchima's body.
Afterward, Black Zetsu had quietly stayed at Obito's side, until this very moment, when he revealed his true colors!
Obito bitterly regretted it. "I should have noticed sooner. If Tsuchima was my will, how could he have learned Flying Thunder God when even I couldn't master it!"
Madara demanded coldly, "Black Zetsu, you tampered with the Uchiha Stone Tablet, didn't you?"
Even knowing the truth, he wouldn't be satisfied until he heard the culprit admit it himself!
Madara and Sasuke were both the same in that regard.
Black Zetsu laid his cards on the table. "I told you not to go to Mount Myōboku. You only needed to lure Jiraiya out and absorb his sage power, but you wouldn't listen. In the end, you found out you were a clown, didn't you? Hahahahahahahaha..."
Madara shook with rage. He clenched his fist, and the Freeform Sage Art markings appeared on Hashirama's face on his chest!
"My sage power has recovered. Black Zetsu, I'll tear you apart!!!"
"Heh... even calling you an idiot gives you too much credit!"
Black Zetsu arrogantly formed hand seals.
"Hm!?" Just as Madara was about to charge, his body froze. "I can't move!?"
Gurgle, gurgle...! Pitch-black fluid welled out across Madara's body!
Black Zetsu said coldly, "White Zetsu has the Spore Technique, and so do I. My Spore Technique uses Black Spores. They're far more subtle and elusive. Even you couldn't detect them!"
Madara's face twisted in pain. "I was already on guard against you. When did you do this!!!"
Black Zetsu sneered. "Heh, I retrieved the corpse you used for your resurrection