A Game of Shadows (Rin Okumura x Reader)

Mayu VS. The Kings

-Rin's POV-

I raced home as soon as my battle with Astaroth ended. Kuro leaped onto my desk as I slammed the door behind me. Yukio jumped at the sudden sound. "Welcome home, Rin. Happy bir-"
"We need to get Mayu over here now!" (Yes, It's still their birthday. It officially lasts all year.) He looked shocked at my sudden outburst. "What!? Why the hell would you want to do that?!" He asked me like I just suggested that we rob a bank or hand Izumo over to the illuminati. (Manga spoilers!) "There's not much time to explain! We just need her ASAP!" I exclaimed as I reached for my phone. I dialed (Y/N)'s, or now Mayu's, phone number and hoped to God she'd pick up.

~Mayu's P.O.V~

Even though it had been about a week since I massacred the rest of (Y/N)'s friends, I was only just recovering my sanity. Hey, I may be the princess of insanity, but I still have saneness. I was wondering if I should do anything to Rin when I heard a loud, obnoxious noise. Doushitatte kanawanai esoragoto darou ga. It was Core Pride. (Y/N)'s annoying ringtone went off. (Fun Fact core pride actually is my ringtone.) I picked up the singing piece of metal. It was Rin. I answered in,a sweet tone. "Hi Okumura! How've you been, honey senpai?" (Kiss Kiss Fall in Love!) "Don't call me that! I know you killed the rest of my friends!" Rin sounded angry. I smirked. "I didn't necessarily kill them, per say. Their bodies were destroyed, sure but their souls still live on. Since they no longer have a vessel to possess, I sealed them away in a separate gem." I explained. "I don't give a crap about them right now! Just meet me in the storage house in Mepphy Land." (Wow Rin, that was kinda cold.) "Anything for you, cutie! <3" I cooed. Rin scoffed and hung up.

~Time skip brought to you by Happy the flying cat~

I did just as Rin had asked of me. I walked to Mepphy Land but was stopped at the front gates.
"It's been quite a while, hasn't it little sister?" I looked up to the top of the gates to see my brothers Samael and Amaimon. A twisted grin formed across my face. "Hello brothers. Fancy meeting you here." "I know you're the reason my students are disappearing Mayu, and I will not allow it." Samael proclaimed. I saw him place a time barrier around us.
"You shouldn't get in my way Samael. Or is it Mephisto now? Either way, I do not wish to hurt you brother. Unless I must of course."
"I know you are after Rin Okumura now and I know why. But please. Abandon this mission. Or I will have no choice but to send you back to Gehenna." Mephisto warned.

"What about Amaimon? He tried to kill Okumura. I'm only fulfilling fathers wish." I pointed out.
"Amaimon grew bored and I warned him that if he did kill anyone, I'd kill him. But he didn't. "
"I'm over Okumura anyways. I got bored of him after I let Behemoth take a chunk of his girlfriend." Amaimon explained. I looked down at the calf of my leg. Stiches were in the form of bite marks. "C'mon Amaimon. Why don't you help me take Okumura's life? It'll be fun!~" I persuaded.
"No thanks. I think it would be more fun to kill you anyways." He declined. I sneered. "I guess there's no convincing you two." I shrugged, summoning my sword. It was similar to Kurikara and could summon my flames no matter what form I was in. I unsheathed it, revealing my blue flames.

"Alright. You asked for this." Mephisto sighed. He took out an umbrella decorated like an ice cream cone and revealed a spear with an hourglass engraved on the blade. Amaimon summoned his pawns. Behemoths, goblins, greenmen, mulkin and chu-chis all came to his aid. I chuckled. "If that's how you want to play it." I dashed forward but was frozen mid-run by Mephisto. Amaimon teleported in front of me and kicked me in the gut. When Mephisto unfroze me, I had the wind knocked out of me. I stabbed a behemoth Amaimon tried sicking me with in the head and used its force to kick him in the face. Amaimon was knocked out. "I always knew you were strong, but I never imagined you could take out Amaimon with one blow. And so easily too. Not even Rin Okumura can do that. Still, I won't let you continue." Mephisto pointed his spear at me. I took a battle stance and did the same. Mephisto leaped forward to stab my head, but I leaped back, resulting with a hole in the concrete. He glared at me. He froze me again and began slamming my body into the ground. (UnderTale Sans battle style!) I forced myself to move and I stomped my feet onto the ground before I could be thrown again. "What!? How are you doing that!? That's impossible!!!!" Mephisto yelled in disbelief. I took my sword and pierced his stomach. "H-how..?" Mephisto asked. "How could I be defeated...so easily?"
"Don't worry. You're a demon. You aren't going to die." I removed my blade and shattered the time barrier. I made my way through the gates and entered the storage house.