A/N: This oneshot is the result of an ask sent by one of my followers on AO3 and Tumblr, and takes place concurrently with Despair Arc Chapter Fifteen in HIMYM. Please read and review, and enjoy!

The Ultimate Detective and The Ultimate Hope Gaiden: Mukuro's Heartbroken Despair!

"What do you mean you're backing out of the plan? We're this close to starting the Killing Game!" Junko demanded, pissed off as Mukuro stared her down and repeated what she said.

"I mean, I want to back out of the Killing Game plan. This past year showed me that I had friends here, people who care about me other than you."

Junko sighed, pinching the bridge of her nose as she tried to bargain "Look, Muku, I already told you, my plan will allow you to have Makoto all to yourself, so…"

Mukuro cut her off "It's not just Makoto anymore! I've come to realize how much I'm valued by everyone else. For kami's sake, Sayaka invited me to sing with her and Kyoko during the Halloween Party, and I got to bond with the others during Hifumi's play!"

"Aww, boo hoo. So you get to bond over some dorky reenactment and a girly concert, and now they're your best friends?"

"They don't have to be my best friends, but they're my friends, Junko! They included me, made me feel like I belonged! At first, it was just Makoto who smiled at me. But now it's most of the others, too! I never thought it would happen, but I have friends now!"

Junko rapped her fist against Mukuro's forehead and pointed out "Uh, hello, Muku, is there still a brain in there? In case you've forgotten, the world's already gone to shit! It's filled with my Remnants of Despair! And little Miss Detective ain't stupid; she's the Ultimate Detective for a reason! Eventually she's gonna figure out it was us who caused the Tragedy! And once they all find out, the last thing they'll consider you is their friend. We'll be lucky if they decide not to haul us off to the Future Foundation to be executed if we don't suppress their memories!"

Mukuro gulped, that exact scenario flashing through her mind before she shook it away, her resolve strengthening as she forced out "Even so, I…I can't commit to this insane Killing Game anymore! I refuse to be the one to lower the axe on their heads. Say whatever you want; I've made my decision! They're my friends, Junko, and I'm going to take a page from Makoto's book and say that I won't turn my back on my friends!"

*Ding Dong*

Steam piped out of Junko's ears, her face livid with anger as Mukuro turned to walk to the door, placing her hand on the doorknob and turning it to reveal…

"…Taka?"

Taka stood there, a serious expression on his face as he began "Mukuro, I need you to relay an urgent message to Junko as soon as possible."

Junko waved and replied "Yo, I'm here, Mr. Hall Monitor. So, what's the big news?"

Taka nodded and instructed "Your immediate assistance is requested in the Gymnasium as soon as possible!"

Mukuro frowned and asked "What happened? Did the Remnants of Despair damage the gates?"

Taka shook his head, smiling as he explained "Oh no, nothing like that. Truthfully, we need all hands on deck to set up a party this evening."

"A…party…?" Mukuro asked, her brow furrowed in confusion while Junko immediately started paying attention to the Ultimate Moral Compass, her attention now caught.

"Yes, a party to celebrate Makoto and Kyoko's next step in their romantic journey! He proposed to her this morning, and the Headmaster has informed us that they're now engaged!"

E…engaged? Makoto's…engaged? Mukuro thought, stunned silent by the revelation.

Mistaking her shock for joy, Taka clapped her on the shoulder and laughed "Hahaha! I see you're so overcome with joy that you lack the words to say it! Worry not Mukuro, you and Junko can show us just how happy you are by helping us in the Gymnasium to prepare for the engagement party! Well, I must be off. See you both tonight!"

As the door slammed shut, Junko grinned, walking up to her gaping sister and taunting "Well, well, Luck Boy actually got the guts to propose. Who knew he had it in him? So, what are ya gonna do about it, sis? You still think they're your friends now that they're letting Miss Detective steal your beloved Makoto from you?"

"O…of course they're my…friends, Junko. I…I knew this would happen e…eventually. I just…need some time to…to digest this, that's all. Then I'll…I'll go and…congratulate them at the pa…party. You'll see, Junko."

"Hmm…well, okay. If that's how you feel…then I'll come to the party too! After all, what party's complete without the Ultimate Fashionista?"

Great… Mukuro thought as she walked over to her closet and started looking for a suitable outfit.

It'll be fine. They're still my friends, even if I'm disappointed…right?

XXX

A nervous Mukuro stood just outside the entrance to the Gymnasium, dressed in her best black dress along with Junko who stood behind her in a similar hot pink dress decorated with white bunny heads that had a diamond shaped hole in the front that exposed her belly.

"Hey, Muku, aren't you gonna go inside? This was your idea, after all."

Mukuro shakily nodded in response to Junko's whispers and replied "Yes, Ju…Junko. Just…checking out the scene of the party is all."

She took out her binoculars and started looking around the room from her vantage point, reading "Congratulations Mr. and Mrs. Kirigiri?" So she didn't even have the decency to take his name, she just made him discard it for her own?!

"Ah, their loss. Come on guys, let's enjoy ourselves!"

Huh? Mukuro looked around to see Sayaka smiling and bidding Kyoko farewell, making the Ultimate Soldier's eyes become downcast as she deduced They were talking about me and Junko, weren't they? So…I really wasn't their friend?

"Aww, what's the matter, Muku? Finally see that these losers aren't your friends?"

"Sh…shut up, Junko. Even if they don't value me after all, Makoto and Kyoko are all I need to…"

Mukuro trailed off, hey eyes becoming blurry with tears as she saw Makoto and Kyoko dance with each other, murmuring words of affection before meeting in a soft kiss. The binoculars fell on the floor, her grip slackened as she felt her heart crack.

I…I knew this was coming…but still…I…why does this hurt so much? Is this…is this…despair?

"Well, what are you waiting for, Muku? Go and congratulate them on their engagement. That's what you came here to do, isn't it?"

Sniffling, Mukuro insisted "I…I will…I just need to…"

Mukuro was cut off as Makoto walked out the door with Kyoko in his arms, the two giggling as they made goo-goo eyes at each other, totally oblivious to the Despair Sisters' presence as they made their way to their room for their engagement night.

They…they didn't even know we were here. I…I really meant NOTHING to them? No…I know I meant something to Makoto…but Junko…Junko was right all along…none of the others cared about me! If only I had taken my chance to be with Makoto while he was still single! Then that…that SIREN wouldn't have been able to ensnare him in her spell!

Mukuro slid to the floor, pulling her knees to her chest and laying her head on them, finally letting out the cries of her heart as it shattered, as though her fractured soul was hit with a bullet.

Junko grinned as she sat next to her sister and rubbed her back in comfort, whispering in her ear "It hurts, doesn't it, seeing him completely ignore you in favor of that Detective Bitch. You know…you can still have Makoto all to yourself…if you want to follow through with the plan…"

Mukuro gasped, her lips stretching into a gradual grin as she realized That's right! If we go through with the Killing Game and erase their memories, then we can kill Kirigiri before she becomes a threat, ensuring that Makoto becomes mine and mine alone! She removed her head from her knees and wiped her tears on her wrist, turning her mascara-smeared face towards Junko as she muttered "…What do you need me to do, Junko?"

Junko grinned as she suggested "Let's take this back to our room, okay? Don't want anyone overhearing us and ruining our plan."

XXX

"Alright, so here's the plan. Hope Boy's probably occupied banging the Detective Bitch…" Mukuro shivered at that particular image as Junko continued "…since it is their engagement night, and the others will still be at the party. So, this is the perfect time to booby-trap everyone's rooms with the sleeping gas mines you prepared."

Mukuro nodded, asking hesitantly "When you say everyone…does that mean…"

Seeing where Mukuro's thoughts were going, Junko replied "Ugh, use your head, Muku! Of course not in Makoto and Kyoko's room! Besides…" Junko grinned evilly as she revealed "Besides, I want Luck Boy and especially Miss Detective to feel the despair of witnessing their dear Father's murder in the Trial Room. Then you'll knock them out with a sleep grenade and bring them to the secret chamber with the others."

Junko giggled while Mukuro nodded uneasily, not exactly ecstatic about knocking Makoto out herself but accepting it as a necessary evil in order to accelerate the plan.

"Alright, but how am I going to get into everyone's rooms?"

*Clink*

Mukuro's eyes widened as Junko dangled a key on a keyring in front of her, the Ultimate Fashionista grinning as she revealed "I swiped it from the Headmaster's Residence while he was busy preparing the party for his little girl and his soon-to-be son-in-law! While he and they are at the party, you'll use this to get into everyone's rooms and plant the mines to release sleeping gas at Five A.M. Once they go off, you'll go and collect everyone while I go abduct the Headmaster from his office and prep him for his execution!"

Mukuro nodded, obeying "Yes, Junko…" as she took the skeleton key from her sister before walking to her closet and opening it.

She then took out a box of mines and carried it with one arm as she used the other to open the door.

"Good luck, Muku!"

Mukuro nodded in response to Junko's wave before she closed the door behind her. As she started walking to the end of the hallway, she glanced at the door she passed by, the plaque reading "Makoto & Kyoko."

Sorry, Makoto, but this is for your own good. I promise…I'll free you from that siren's slimy grasp!