~3rd Person P.O.V~
Y/n ran towards Shalba as he created a bunch of magic circles sending a bunch of attacks at Y/n, but he dodged or parried a few of them with Playful Cloud. Y/n used the chains of a thousand miles and threw it at Shalba as he dodged it and grabbed the chain before spinning it around and throwing Y/n out of the castle.
Y/n: So you weren't all talk weren't you? Not like that Astaroth bastard.
Shalba: Of course not. Unlike him, I have my own power for being an old Devil King mixed with Ophis power who is a Dragon God.
Y/n: You could provide some fun for me. Let's go. Overtime begins now.
Shalba: Do not take me lightly!
He rushes towards Y/n while preparing a magic circle on his hand, but Y/n uses Ratio Technique: Collapse on the ground causing an explosion blasting Shalba away and destroying the castle.
Shalba: Bastard!
He stood up gathering magic in his palms and throwing it at Y/n. The attack destroyed everything in its path as it hit Y/n causing a huge explosion. When the smoke cleared, Y/n was still standing but his Balance Breaker was destroyed as well as his shirt and he had a bruise on his chest.
Shalba: Haha! I told you that you will pay for mocking me!
Y/n: Let's call that a 'Lucky Shot'. Ddraig.
Ddraig: Yes, Lord Y/n.
Y/n: We're going to do 'that' thing.
Ddraig: A-Are you sure, Lord Y/n? That will leave some strain on your body.
Y/n: We're just doing a test.
Ddraig: Very well, Lord Y/n.
Y/n & Ddraig: I, who am about to awaken,
Am the Heavenly Dragon who has stolen the principles of domination from God
I laugh at the "infinite", and I grieve at the "dream"
I shall become the Red Dragon of Domination
And I shall sink you to the depths of the crimson purgatory!
Y/n's Balance Braker slowly started turning into a giant humanoid Dragon with skeletal wings. Shalba couldn't do anything but watch Y/n transform in horror. A few seconds later, Y/n finished transforming while still holding Playful Cloud which grew to his size.
Y/n: Let's keep going.
Shalba: That shouldn't be possible! The Juggernaut Drive isn't supposed to be controlled easily!
Y/n: Idiot. A hierarchy not based purely on strength is boring if you ask me. This is pure strength.
Y/n rushed at Shalba and kicked him away as Shalba spread his wings and flew back towards Y/n shooting magic at him.
Shalba: I will not be defeated by the likes of you, Red Dragon Emperor!
He did the same attack before but the attack was a little bigger. He threw it towards Y/n's chest as it hit him directly.
Shalba: Haha! Even if you are in Juggernaut Drive, you cannot survive a Devil King's attack!
When the smoke clears, Y/n was still standing as nothing happened. Shalba's eyes went wide to see Y/n still standing even though he put all of his power into the attack.
Y/n: You really are boring.
He didn't say a word as his eyes were still wide and Y/n rushed at Shalba and grabbed him by the neck and threw him to the ground causing a crater. Shalba is now crawling out of the crater with fear on his face and he doesn't have enough power to continue.
Y/n disable his Juggernaut Drive and went back to Balance Braker. He flew down and walked towards the crawling Shalba. He kicked him in the face making him lay on his back.
Y/n: Don't start what you can finish.
He grabbed Shalba's head and threw him against a boulder as he spits out blood from the impact. He grabbed his leg and slammed him on the ground as Shalba was screaming in pain at the top of his lungs. Y/n is now punching him in the face, kicking him in the stomach resulting in a broken nose and ribs.
Y/n then summoned the Inverted Spear of Heavens as it made Shalba shocked at the realization.
Shalba: T-That Spear! I-I-It's...Y-You?!
Y/n: Yeah, The King of Curses.
He trusted the Spear in Shalba's stomach as he screamed wildly. Y/n turned and saw the remaining terrorist devils behind him as he placed his hands together forming a sign.
Y/n: You've shown me the way, Shalba Beelzebub! Domain Expansion: Malevolent Shrine.
As soon as the shrine appeared behind him, Y/n used cleave and dismantle cutting the entire area in front of him killing all of the terrorist devils.
Y/n went back to Shalba who had a face of honor witnessing the true power of the King of Curses.
Shalba: I guess this is a fitting end for a Devil King who wanted to destroy the underworld.
Y/n: You wanted to destroy the underworld? I wouldn't understand your actions, but there are people I care about here. Though you did provide me good fun so stand proud, your strong.
Shalba's eyes widened before he felt something wet down his cheek.
Shalba: What is this?
Y/n: Don't ask me. Figure it out yourself.
Y/n used his secret command to burn Shalba's body as his body turned to ash. Y/n disable his Balance Breaker and unsummoned the Inverted Spear of Heavens before he fell to his knee feeling dizzy.
Y/n: Guess I overdid it, huh?
Ddraig: Yes, you did. If you weren't a King, you probably wouldn't survive the transformation.
Y/n: Looks like I still have a long way to go.
???: N/n?!
Y/n looked up to see Rias and the ORC along with Azazel flying down to him.
Y/n: Hey everyone, you alright?
Rias: We're fine. What about you?
Y/n: Never better.
Azazel: I happen to receive news that the enemies had backup here, but I didn't see them.
Y/n: Then your not looking hard enough. Look behind me.
They all took a look behind Y/n and were shocked to see a barren land with dead bodies.
Azazel: Looks like we didn't have to worry about that.
Y/n: Can we get out of here. I'm tired.
Rias created a magic circle on the ground and teleported everyone back to the house while leaving Azazel to look for any enemy survivors and to report what happened.
Y/n: I've never felt so tired before.
Kuroka: You guys are back. How was the Rating Game?
Y/n: It didn't go as it should have.
Kuroka: What do you mean?
Rias: The Rating Game has been canceled due to Diodora Astaroth being allied with Khaos Brigade.
Kuroka: What?! Shirone, are you alright?! Are you hurt?! Oh, I'll make them pay if they hurt a single hair on you!
She was hugging Koneko as their cheeks rubbed against each other.
Koneko: O-Onee-chan, I'm fine! They didn't hurt me! Onii-chan protected us from them!
Kuroka: Looks like I'm gonna reward your Onii-chan later~
Y/n: I feel like I don't want to know.
Kuroka: Rias, can I talk to you in private?
Rias: Sure, you guy can go rest now.
~Timeskip~
Everyone went to their rooms while Y/n went to the kitchen to have something to eat. After eating, he went up to his room and entered the bathroom taking a shower and getting dressed into something comfortable before laying in bed. All of a sudden, he felt someone crawl on top of him as he opens his eyes to see Kuroka with a lustful face.
Y/n: Kuroka, what are you doing here?
Kuroka: Well Y/n-kun, you already know me and Shirone are the last of our kind, right~
Y/n: Yeah...
Kuroka: And we wanna repopulate our kind and it just so happen that it's our kind's mating season~
Y/n: Y-You mean...
Kuroka: Yup, we're going to make some cute little kittens together~
She mashed her lips with his trying to insert her tongue inside his mouth, but Y/n grabbed her shoulders to stop her first.
Y/n: Is this what you wanted to talk to Rias about?
Kuroka: Yep. She understood completely.
Y/n: Alright.
Y/n kissed her again and their tongues fought for dominance, but Y/n easily won and started exploring his new territory. Kuroka sat on his chest and undid the sash of her kimono letting it fall off her body and giving Y/n a clear view of her chest.
Kuroka: Like what you see~
Y/n smirked and let her sit on his lap while he sat and sucked on her left breast while he massaged her right breast.
Kuroka: Ahh~ Yes, keep sucking them~
Y/n kept sucking on her breast alternating from right to left while Kuroka kept rubbing her womanhood against his manhood trying to make it erect.
Kuroka: It's not fair if I'm the only one that's naked here~
Y/n laid Kuroka on the bed before removing his clothes leaving his boxers with a tent in them.
Kuroka: Looks like someone's excited~
She crawled towards him and massaged his manhood with her hands. She removes his boxers letting his erect manhood hit her face.
Kuroka: Oh my~ I'm going to enjoy this.
She stroked it first before licking the tip as she sucked on the head slowly taking more of it in. She started to suck faster and faster before Y/n felt his climax coming.
Y/n: Kuroka, I'm close.
She kept sucking it until he released all of his load into her mouth. Some of it leaked out of her mouth as she used her finger and licked it.
Kuroka: Yummy~ Thanks for the appetizer~ Now, it's your turn~
She lay on the bed and spread her legs while Y/n started to finger her as she moaned. He kept inserting his finger while playing with her clit.
Kuroka: Ahh~ Yes~ Keep going~
He removed his finger and started licking her womanhood while inserting his tongue inside of her. She kept moaning louder as he licked her insides while Kuroka grabbed his head to keep his mouth in place. She then came inside of his mouth as he drank it all while she lay on the bed.
Y/n: You still good to keep going?
Kuroka: Don't worry~ I can still go for more~
He rubbed his manhood against her entrance teasing her.
Y/n: Are you ready?
Kuroka: Of course I am~ Now, stop teasing me and give it to me~
He slowly insert it as she grits her teeth and gripped the sheets before he fully inserts himself inside of her as he saw some blood dripping and tears in her eyes.
Y/n: Are you okay?
Kuroka: Y-Yes, you can start moving now.
Y/n started to thrust his hips back and forth as her breast bounced as well. Y/n grabbed her right breast squeezing it while his other hand was holding her hand.
Kuroka: Ahh~ Don't stop~ Keep hitting me there~
He laid her on her sides while putting her foot over his shoulder as he continued to thrust in her while she was moaning. Her face was getting redder and redder while her tongue hung out of her mouth as she was breathing heavily.
Kuroka: Ah, yes~ Y/n~ You're going to break me~ Keep going~ Destroy me~
He kept on thrusting before he felt his climax coming.
Y/n: Ugh, Kuroka...
Kuroka: Do it~ Inside me~ Release it all inside me~
With a final thrust, Y/n released all of his load inside of her as she moaned loudly. He pulled out of her as his load was dripping out of her and she was panting.
Kuroka: Haa~ Haa~ That was~ Amazing~
Y/n: Yeah, I can sleep now.
~Lemon End~
Kuroka waited a few minutes to gain feeling back into her legs as she sat up and put her panties back on while putting on her Kimono again.
Kuroka: See you, Y/n~ Let's do this again sometime~ Because that was very fun~
Y/n: Yeah, it was. See you tomorrow.
Kuroka: Oh, I forgot to mention. Shirone will be in her mating season too so she might need help~
Y/n: What?! What am I going to do?! She's like a little sister to me. I don't know if I could do that.
Kuroka: Don't worry, I can do something about that. But she'll need to release her mating urges or else she will lose control~
She left the room closing the door behind her as Y/n thought about Koneko's situation.
Y/n: I'll think of a solution somehow. Right now, I need to sleep.
~~~~~~~~~~~~~
~~~~~~~~~~~~~~