Haru spreads all his senses and determined the exact location of Zetsu, he then teleported towards him. Well Haru places his seal behind Zetsu when he confronted him to give his warning.

When Haru appeared before Zetsu, he knew that Haru will come to him so he was not surprise about that.

He then said to Haru "Follow me Madara-sama wants to meet you"

Haru said nothing and just followed Zetsu, they went to a cave and went underground. 

When Haru came into it he was on a large space underground with a huge scary looking statue at the back, he then look before him and saw an old man with spiky long white hair staring at him.

He paid him no mind and looks around to search for Obito and he found him unconscious on a bed. He heaves a sigh and look back at Madara. He maintained eye contact and both Madara and Haru's momentum are slowly increasing until the cave shook with their sheer momentum alone.

Haru's momentum keeps increasing until he surpasses Madara's. Madara was shock that someone bested him in his momentum. 

Looks like what Zetsu said was true, his momentum keeps increasing until Madara was sweating coldly and he felt that he was in front of a god that looks at him like an insignificant ant. 

Madara is slowly kneeling on the ground until he could no longer take it and totally knelt, only then did Haru retract his momentum. 

He went towards Obito and checks his physique and concluded that he was just unconscious. He then checks his mind and noted a seal was formed in his memories, he then look at Madara coldly and bound Obito in his chains.

"Hahaha looks like you are aware of what I did, either way I will tell you, I lock up Obito's memories and he will only remember pure rage towards Konoha" said Madara

"Madara it looks like you forgot my warning or probably just shrug it off, but either way now that I'm here I will deal with you" said Haru coldly

"Well it is true that in my current state I will not be your opponent, but I am Madara Uchiha and I will not bow down to anybody."

'But you just knelt before me though' thought Haru

After he said that black rods where shot to his back from the Gedo Mazo statue and Madara's old body is back to his prime, his sharingan in both eyes swirled and evolve to mangekyo sharingan.

He then look at Zetsu and said, "If I will die here tell Nagato to reincarnate me as soon as possible."

"How about Obito?" ask Zetsu

"Well when he woke up he will search for you since I already sealed his memory and only I can unseal it" said Madara confidently

"Follow the preparation I told you" he then added. 

After that the black rods which are connected to the statue broke and the statue disappeared in a puff of smoke.

Haru then manifested his phoenix wings, and unsheathe his zanpakuto. He wave a sword slash towards Madara and Madara summons his [Susanoo], a sword appeared in his hands and tried to deflect the sword slash but the slash was powerful enough to have him take a step backwards until he reach the wall.

He was shock by Haru's powers, he then look at him and said "Looks like you are stronger than the rumors, we will take this outside"

He then broke through the ceiling of his cave and flew up, Haru also follows suit while holding Obito.

When they are outside he laid Obito down and summons Akai, he told Akai to take Obito and move far away. Obito was still bound by Haru's chains so he won't struggle and run away until Haru remove his seal.

Akai took Obito and run, Haru then look up to Madara and he flew up. He then said 

"Let's see the strength of the legendary Uchiha Madara" said Haru

"Hahaha only Hashirama have the right to say that to me kid, show me your strength or the strength of this generation" said Madara 

After he said that his Susano which is only a half body skeleton evolve; the half body skeleton grew up and become full body, flesh, skin and armors were place on it and the half ass susano evolve into a full body susano, with a gigantic sword in its hands.

Haru saw this but instead of getting intimidated he was excited instead, since he will fight with one of the strongest here in Naruto world. Although the old man just uses the chakra of the Gedo mazo and uses his vitality to fight him and is weakened, he is still looking forward in this battle.

Madara saw Haru's excited expression and could not help to also be excited, since his rival Hashirama was dead, he longed for the thrill in battle, and a strong opponent is in front of him. 

Truthfully he can just avoid this battle and let Haru joined him, but he doubted that this kid would want to join him, so that's why he already prepared everything before he left this world.

He is on his death bed anyway, but if he can try and fight a strong opponent before he departs in this mortal realm, he is going to take this chance and fulfill his intent to battle. 

Obito is only a play safe in his plans he really did not need him but he have to give a reason to Haru to fight him, but it is still true about the seal that he place on Obito's mind.

"Make sure to entertain me kid, fulfill my intent to battle strong opponents. If you are really as strong as the rumors say you are then take this attack of mine, since Hashirama is the only one who can take my full powered attack" said Madara before he wave his sword down towards Haru

Haru just stayed on his place, he already activated his sage mode and his appearance changes from a gorgeous angel to an enchanting devil. He coated his arms and katana with armament haki and met with the sword strike from Madara's susano.

The size of Haru's sword and Madara's sword is like comparing an ant to an elephant but the power on Haru's sword is much stronger.

Haru fully blocks Madara's attack and the shock wave shook the surrounding environment they were in.

Madara was surprise to see that Haru truly blocks his attack; Haru then uses his strength to deflect the sword above his head after which he sent a sword slash towards Madara, Madara put his sword on the Susano's chest to defend against Haru's slash and the Susano skidded away due to the force of Haru's attack.

Haru look at Madara in a mocking expression "Is this the strength of the previous world's strongest it's just so so"

"Don't be arrogant brat" said Madara he then made another sword in his hands and the Susano now is holding 1 sword each hands.

Madara then let the Susano jump and went towards Haru, Haru uses his sword to deflect each of Madara's strike. He felt that he is very close in stepping to grand-master level so Haru uses his sword technique to fight Madara.

After a while Madara keep on pressuring Haru and Haru is having a hard time defending against him. 

'Damn Madara really is strong, I am having a hard time dealing with his attacks, although I can see his attacks he uses two swords which are fast enough to counter.' Thought Haru

Well this is the first time Haru limits himself to fight only using his swordsmanship, so he is having a hard time dealing with Madara's onslaught.

Madara is also having a difficult time fighting Haru, but he is excited to finally battle an opponent stronger than him.

"Hahaha Finally a worthy opponent" said Madara

"You really are a battle maniac" said Haru

'Damn I don't think I can win with only using my swordsmanship' thought Haru but still he did not use any other techniques, he believes in his own sword that he can do it, he can dominate the world, and he can burn everything to ashes.

And then something incredible happened, Madara's sword in front of him became very slow that Haru can easily deflect it, he was lost in his own enlightenment that his sword strike became more domineering and moves faster. 

He felt that he can sense the intent of the world and he unconsciously uses this intent towards Madara.

Madara felt that his surrounding became very sharp like blade, his clothes although he had the protection of Susano are being cut and a cut was also seen on his right cheeks. His eyes widen and look at Haru incredulously.

'So this kid is using me to breakthrough!' thought Madara 

"DAMN YOU BRAT!"

Madara then strike faster and faster, but Haru just keep deflecting and parrying his attacks. 

Haru's using his sword domain to keep attacking Madara. Yes right now Haru just broke through and now he is a sword grand-master, he can now use his domain to attack others, and his domain contains fire elements that each cut has a burning effect on it. 

After exchanging blows they separated.

Haru look at him and grin he then said 

"Thank you Madara for your assistance"

Madara gritted his teeth in anger, since in the beginning of the duel he uses his full strength to fight Haru, and Haru is just using him as his way to break through.

"Damn Brat! I never expected you to use me as leverage for your breakthrough; I Madara won't accept this humiliation!"

"Hahaha this is my punishment for you Madara, A battle junkie like you won't tolerate something like someone underestimating you."

Madara then attack Haru in a frenzy

"Ora! Ora! Ora! Ora! Ora! Ora!" (Madara)

"Muda! Muda! Muda! Muda! Muda! Mudara!" (Haru) (a/n: pun intended LOL)

After a while they separated again and Madara's look became old again by using too much chakra.

Haru then said "You don't know the true meaning of being the strongest"

"To be strong means you have someone you have to protect, and that feeling for your love ones will be your drive to become the strongest" said Haru

Madara while catching his breath looks at Haru and said calmly

"Don't lecture me about trying to protect someone brat, I had been alive long before you are still breastfeeding with your mommy. 

I have seen the wickedness and cruelty of this world, and no true peace was seen.

 What it means to become strong? It is to attain power and to control the entire world that is what it means to become strong and not your naïve concept of protection." 

"I see, then I'll just show you what it means to have the power to protect"

[All things in the universe turn to ashes, Ryugin Jakka] 

Flames covered his sword and Haru was surrounded by intense flames, his scarlet hair flows with the wind he looks like the divine phoenix that descends on the world.

Madara felt the heat from Haru's flames and noted that the heat can burn his susano but he did not give up he looks at Haru seriously, he then uses his entire chakra reserve to increase the defense on his susano. Haru looks at him and said

"This is true power Madara [Ennetsu Jigoku]"

Pillars of flames sprouted from the ground and engulf their surroundings, Haru wield his flames toward Madara, Madara wave his sword towards the flames but the flames melted his sword, he also uses his [Amaterasu] but how can the black flames compared with the real flames of the sun, the black flames were engulf by the flames and the susano melted and burned.

After that Haru sheathed his katana and the flames dwindle until it disappears. What remained is a burned forest, he look at the human shape ash on the ground.

"That is true power" said Haru before disappearing and went towards Obito. 

After Haru left Zetsu appeared in the burned battlefield and said 

"Looks like Madara really lost we need to fasten the plan, only mother can deal with that kid" he then disappeared down the ground.