Madara reminisced of the past.
Prior to one of his battles against Hashirama, an Uchiha had given him a "treasure" called the ender pearl. At first, he was doubtful of the pearl's usefulness. But throwing it at Hashirama, both men were startled when Madara suddenly appeared infront of Hashirama, armed with his perfect Susanoo.
Thanks to the shock, Hashirama was forced to flee from Madara for the first time.
Unfortunately, due to his carelessness, he couldn't utilize the pearl properly, and Hashirama became alert of the item. Not to mention, during the three years the Uchiha owned the portal, they only gathered less than three dozen ender pearls. Each were used strategically, and now, only ten remained.
"From what I've heard, it takes a hundred Uchiha three days to ignite the portal with their chakra," Madara scoffed. "Pathetic. The clansmen haven't been training enough. Let me show you how it's done." He raised his hand, pointing his palm at the portal.
Closing his eyes, he gathered his chakra, infusing it with fire affinity and then sending it toward the portal frame. Like a black hole, the empty portal frame absorbed his chakra.
"Hmm?" Madara's eyes twitched, sensing his chakra reserved draining. "I see now, no wonder it's so difficult for all of you."
With a smirk, he opened his eyes, his sharingan activating, followed by his mangekyo sharingan. Then, his chakra subtly changed—yin chakra nature mixing with it in minute amounts.
As if a camel dying of thirst, the obsidian frame trembled, and a swirling purplish sheet appeared in the middle of the portal frame. Within seconds, the portal membrane expanded, filling up the entire portal frame and activating it.
"Hmph," Madara grunted, brows furrowed. 'It took two-thirds of my chakra reserves,' he thought, secretly masking his exhaustion.
Even while fighting Hashirama, the two of them would fight for hours before either men—usually him first—showed signs of chakra exhaustion. Thinking about it, Madara scoffed.
"Now what?" He turned to the Uchiha behind him. From what he knew...
Suddenly, the portal membrane trembled. A long, sorrowful wail echoed from beyond. Slowly, several white tentacles the size of human torso stretched out of the portal, probing the portal frame. However, the tentacles quickly retreated.
"What was that?" Madara asked, crossing his arms. He'd seen his fair share of anomalies, butbhe couldn't describe what he'd just seen.
"We don't exactly know, patriarch. Our theory is that it's too big to exit he portal, judging from its limbs," the Uchiha replied.
Madara nodded. Not long after, the portal trembled once more. This time, a different entity walked out, its steps cautious. It was tall, taller than both Uchiha by more than one meter. It's skin was pitch black emanating purplish particles, it's eyes an enchanting amethyst. And it's mouth...
"RRRAAAAH!!!"
The entity opened its mouth in anger, its eyes staring straight into Madara's mangekyo sharingan.
***
Naturally, I wouldn't drop down that dark tunnel. I didn't put water down there—I placed a "shallow" three block deep lava pool. It's a kind welcome, and if ninjas really get there, I can just keep dropping down stalactites (dripstone).
That being said, I belatedly realized I don't have a plan of how I'll return safely when I go back... I guess I'll save all my ender pearls if possible.
Now then, time to dig. This new portal should manifest on a different location. The shinobi world... I wonder if I can learn their ninjutsu.