He exited that tunnel a while ago. After a long day of running, he entered the Land of Sound and is nearing the Otogakure village.
Having used his Tenseigan chakra mode for a few seconds before, coupled with him running the whole day in high intensity, he now had only 70% of his original strength left.
'But it'll be more than enough for Orochimaru' he thought. As for why he needed to go against Orochimaru, it would be because he needed to set things straight between the two of them.
A few hours after, he entered the Otogakure village and was standing near the entrance of the Orochimaru's base. He said the secret code to the guards and entered.
He soon came to a large courtyard inside the base, and as expected Orochimaru was waiting for him there alongside Kabuto.
"You look a lot stronger and healthier than the last time I saw you." complimented Kabuto.
"I see you managed to cure your illness. Impressive. Considering that even Kabuto couldn't do it. I'm wondering just how much you know..." Orochimaru hissed.
"I managed to do a lot of things in these two years. And yes, one of those things was curing that stupid illness." Kimimaro replied.
"Did you manage to do that thing you promised, as well? What's that on your back?" Orochimaru asked in a somehow excited voice.
"It's Sasuke Uchiha!" Kimimaro said as he laughed and opened the cage, then closed it up again.
"Just how on earth were you able to do it...? And are you sure it won't be traced back to me as you said?" Orochimaru asked, just to be sure.
"Yes, in fact, I found a perfect scapegoat to take the blame for it too hehe" Kimimaro smiled.
"Hmm, let me guess, it is probably Danzo..." Orochimaru guessed.
"Jackpot" Kimimaro said, then continued: "But before we continue our talk, I guess we should set things straight between the two of us and change our previous relationship from master and servant. To full-fledged partners" Kimimaro smiled.
"Ooh? Are you sure you're qualified for that? I know you improved a little in these two years but you shouldn't let it get to your head, kid" Orochimaru replied a little provoked.
"Kabuto move back a little bit!" Orochimaru said. Then he separated his torso from his legs and moved fast toward Kimimamo like a real snake. Once he got closer he opened his mouth.
'He wants to bite me and use some kind of seal on me' Kimimaro thought.
"Giant Bone Drill" He yelled and made a giant drill from his forearm bones. Around two meters long and one meter wide. More sturdy and overall more giant bone drill than in the original.
He slashed it at the incoming Orochimaru effectively destroying him.
"C' mon Orochimaru, attack me with everything you've got. Better don't underestimate me or you'll regret it"
Orochimaru regenerated and looked at the giant drill then said: "So this was the potential of your Kekkei Genkai all along?"
"You've seen nothing yet, c' mon!" He moved fast and attacked.
Orochimaru moved like a real snake around with his tail on the ground. Moving around, evading every attack, looking to come behind Kimimaro and attack him from there. Looking for an opening.
From the safe distance. On the balcony looking at the courtyard from the Orochimaru's base.
Three kids sensed the commotion and looked over.
The orange haired kid said: "Kimimaro..."
The white-haired one asked: "You know him Jugo?"
He responded: "Yes he was my friend I talked about before"
The red-haired girl with glasses said: "Kimimaro? Wasn't he the most promising person under Orochimaru? That one that just disappeared all of a sudden two years ago?"
Jugo responded: "Yes, it seems that he came even stronger now"
White-haired tee snorted: "Impressive Kekkei Genkai ability and all. But who does he think he is to go fighting against Lord Orochimaru like that?"
Jugo responded: "I don't know, let's wait and see"
On the battlefield. Kimimaro got tired of playing hide and seek with Orochimaru. He dissolved his bone drill and said: "It's time to get serious now"
He clasped his hand on the ground and said: "Sawarabi no Mai"
The whole ground trembled and soon giant bone spikes appeared one after another from the ground effectively covering the whole surface of the courtyard. Kimimaro disappeared and blended into them.
This was the strongest attack he displayed in the original series.
Kabuto and others looked so shocked after the attack that they couldn't even speak.
Orochimaru launched his head 50 meters into the air like in his fight against Naruto in the original.
He looked down on the battlefield. His mouth already spitting out a sword, ready to attack Kimimao as soon as he showed himself.
Kimimaro soon exited from one spike saying: "Bone Canon" and started launching hardened bone projectiles at the Orochimaru's head up in the air.
'So you're there' Orochimaru though. He moved his head down at an extremely fast speed while dodging every incoming projectile aiming at him. Sword in his mouth ready to strike.
'I got you!' he thought as he was now really close to Kimimaro's position. He launched a prolonged sword from his mouth aiming for Kimimaro.
But, Kimimaro just smiled and clasped his hands. Soon some of the bone spikes from the ground started growing even more and gained a flexible shape. Effectively closing in on Orochimaru to trap him.
'Not good!' Orochimaru thought. His head got trapped. But his body revived again from the part left on the ground. He tried to go the underground and escape from this field as Kimimaro had the biggest advantage here.
But as soon as he entered the underground, he realized that the earth is fully mixed up with some kind of white substances. Kimimaro's fluid bones. He prepared this in advance.
Soon the fluid bones started entrapping him like a tornado, then hardening, then molding, finally making a bone cage for himself.
Kimimaro got to the cage and said: "Can we talk like partners now?" Only Orochimaru's head was visible, everything else was trapped in bones.
"Okay, what do you want?" Orochimaru asked grudgingly.
Kimimaro smiled: "Location of the Ryūchi Cave, as well as all your knowledge on Fuinjutsu, especially tailed beast sealing techniques"
He needs the location of Ryūchi Cave for training in senjutsu. And he needs sealing techniques to prepare for sealing Black Zetsu away and sealing Ten-Tails inside himself to become its Jinchuriki.
"I'm assuming you're aren't asking for that for free" Orochimaru replied.
"I'll give you Sasuke Uchiha and the secret of unlocking Rinnegan" Kimimaro replied grinning.
He knows that he can't exhort these two things from Orochimaru for free.
Even if threatens to kill Orochimaru, he could just come back alive from some unknown curse mark in the world and never give him the things he wants.
Orochimaru looked shocked 'Rinnegan...'
"Okay, we have a deal!" He said. Not even asking how he knew the secrets of Rinnegan.
He let him free. Then dissolved all the bones in the courtyard. Kabuto came here as well looked somehow relived. They entered the building.
While Kimimaro was waiting for the things he came for, three people approached him.
Two of them looked silent while Jugo said: "Long time no see Kimimaro, can't believe you took down Lord Orochimaru like that"
"There's always going to be someone stronger than you" Kimimaro said.
The two talked a little when the red-haired girl with glasses said all of a sudden said: "Please take me with you!"
Kimimaro looked a little taken aback, then asked: "Why?"
"You're so cool! I want to go with you. Please take me from Orochimaru" Karin replied excitedly with a blush on her cheeks and stars in her eyes.
"Sorry, but I can't. I have a lot more things to do alone and will probably be dragged down by you.
Not to mention you're not my type. I like blonde girls and I hate girls with glasses" Kimimaro replied jokingly.
She looked a little sad but determined as well.
Soon Kabuto called him in. Orochimaru was waiting for him and they exchanged things.
After he gave him Sasuke and verified what Orochimaru had given him, he said: "The secret to unlocking Rinnegan is very simple. You need to have either Senju or Uchiha body. Then you have to implant cells of the other one. Example, if you have an Uchiha body. You need to implant Senju cells. If you have Senju body, you implant Sharingan. That's the gist of it, but you need to research a bit more" he didn't tell him about Indra and Ashura because Orochimaru didn't know about them at this point in the series.
Orochimaru looked lost in thought. Kimimaro said: "Goodbye for now" and left.
While traveling to the Ryūchi Cave. Kimimaro reflected on his fight against Orochimaru.
The reason why he didn't use Kekkei Mora against him was that it simply wouldn't work, because he would always shed a new body after he destroyed his previous shell.
He also had a couple of stronger bone attacks, but Orochimaru also has Edo Tensei and that giant Hydra.
But either way, he managed to gouge that he would win against Orochimaru in any case, even without using Tenseigan.
'I've gotten really strong' He thought.
After mastering the Sage Mode he would be even stronger, managing to win up against anyone other than his clan ancestor Kaguya probably.