The case had been easier than Yako had anticipated, and as such hadn't required all that much work. Simple really; she was amazed that the police hadn't been able to solve it.

But then again, most cases she was presented with these days were quite easily solved. Nothing really seemed difficult anymore. She was really managing to make a name for herself; this hadn't been her first international trip, though this was the first time she'd worked for a military force.

The high-school detective had grown into the famous woman super-sleuth Katsuragi Yako; still in her teenage years, yet with more solved cases under her belt than police detectives three times her age, and with a popularity starting to rival Sherlock Holmes.

Gossip magazines always managed to have at least one article on her every month, whether it was speculation into her private life ('Famous super girl detective seen with mystery man!' – always a work colleague, or Godai at one stage), or senseless rage about her eating habits and how she never gained a single pound (she couldn't count the number of times she had been accused of being bulimic).

But Yako didn't mind; she loved her life. She loved the feeling of solving mysteries that boggled the minds of everyone around her, catching devious serial killers and saving lives. It always gave her a sense of nostalgia. Her thoughts would always drift to Sasazuka, and she knew inside that he would be proud of her.

--

As Yako settled down in her seat, ready to spend the rest of the flight in slumber, she couldn't stop her eyes sliding over to the window. She had always enjoyed watching the clouds whilst flying, and it was a beautiful day for observing; the clouds were thick and fluffy, and she could see the ocean far below, glinting in the sun. Her catch-up sleep could come later.

The clouds floated past as the plane flew on, and Yako felt her eyes slowly starting to droop. Her head rested gently against the frame of the window, still gazing at the sky. Suddenly, she saw a flash of blue appear on the wing.

"What the hell?" she murmured to herself, rubbing her eyes. When she moved her hands away, however, they snapped open in shock at the figure standing on the wing, jacket flapping in the wind, hair splayed across his face, staring right at her with a devious grin.

Yako slowly closed the window.

'I must have dozed off', she thought to herself, gingerly removing her fingers from the window cover. 'I must be in a dream…' In the back of her mind, she noted that in the past, she would have thought of such an event as a nightmare, but not now.

She wondered why that was.

Shaking off such thoughts, the teenager (oh god, I'll be twenty in two months…) dug her nails into her forearm, in order to determine whether or not she was in fact asleep. When both the pain and her reality appeared to be real, she slowly raised the window cover.

His face stared back at her, pressed against the glass, with that stupid (wonderful) grin plastered across his lips. One monstrous claw tapped on the window.

Yako slammed the cover down this time.

'Right. Okay.' she thought. 'I knew I shouldn't have drunk the water in that place.'

Dimly, she could hear a steward asking her something about food, but nothing seemed to be registering.

"Sorry?" she asked, dazed.

"I said, maggot, would you like some peanuts?"

"Oh, no thanks, I'm actually-" Yako paused.

Did he…did he just call me…

The detective turned to face the man addressing her, and wasn't really all that surprised when her eyes met a pair of glowing green ones. Neuro grinned, and waved the bag of nuts in her face.

"What's the matter, earthworm? Not hungry?"

Yako gulped. Thank god he's not wearing a steward's uniform. I don't think I'd be able to handle that.

"Not for your nuts, Neuro." Yako replied coolly, and then paused.

Oh god what did I just say-

"Are you implying that there is something wrong with my nuts?" Neuro asked, raising an eyebrow and leaning casually against the seat.

"I'm not implying anything about your nuts!!" Yako half-screamed, fighting to keep her face from turning into a beetroot, a battle that she lost once she realized half the plane had heard her outburst.

"There's no need to get so anxious, maggot. You can have my nuts in your mouth whenever you like; that's why I'm offering them to you." Neuro's face would have been the picture of innocence had his eyes not been glowing like a neon sign.

'The bastard, he's doing this on purpose!' Yako seethed, more for the fact that she was feeling emotions very different to anger amongst all this…stupid innuendo, emotions that she had thought she had buried when her demonic boss had disappeared from her life 3 years ago.

"Just…just give them to me!" The detective snatched the packet out of Neuro's hand, and shoved them into the seat pocket. Neuro's grin widened and he slid down into the seat beside her.

"You can never just enter gracefully, can you, Neuro?" Yako sighed, slumping down into her seat. "It's always a drama when you're around."

Neuro's grin didn't fade. "I'm pleased to see you too, partner."

With those words, a memory immediately flicked into Yako's mind, and she couldn't restrain a slight blush, suddenly finding her shoes absolutely fascinating.

"How is my slave going?" Neuro asked suddenly. Yako blinked, not knowing to whom he referred.

"Oh, you mean Godai?" Neuro nodded. "Very well; he's actually running the information company. We keep in touch a fair bit; he's really turned his life around." Yako said with a smile.

"Very good; I shall have to pay him a visit." Neuro replied, narrowing his eyes, linking his fingers and grinning like a madman. Yako half expected him to start cackling.

She also dimly noted that he didn't include her in his list of slaves anymore.

"Well, maggot, you've certainly changed a bit, haven't you?" Neuro said, pulling rather sharply at Yako's now longer hair.

The name calling was apparently here to stay, however.

Yako smiled. "And you haven't changed at all, Neuro."

Neuro just grinned.

--

"Did you manage to sort things out in the demon world?"

"Mhm; I hadn't realized things had gotten so out of control with my absence. I have to head back soon."

"Already? But you just got here!"

"Truth hurts, earthworm. You're quite welcome to accompany me, you know."

It was Yako's turn to raise an eyebrow. "You're asking me to go to hell with you?" she asked, amused.

However, when Neuro slowly turned back to face her, a lazy smile etched across his features, something in Yako stirred as she looked at him, and she realized that she had never seen him look so human.

"If you want…maggot."

They sat in silence for a little while. Yako stared out the window, but the clouds held no interest for her anymore.

"Neuro…" she said softly. "I…I don't think hell is really the place for me. I mean, what am I supposed to eat?" she joked, but the humour died on her lips when she turned back to him, watching her with such serious eyes, and she realised she didn't feel so good.

"I understand; it was illogical for me to ask. It's just that I'm not sure of the next time I'll be able to return to the human world. Duties in hell, you see. All I know is that the period of time between my visits is going to increase rather dramatically."

Yako began to feel worse.

"You mean...more years will have passed for me?"

"Far more than this, yes."

"...oh." And with that revelation, something in Yako snapped. The delicate vault in which she had stored all her emotions relating to the demon began to break apart, and the contents spilled outward and upward, until tears began to form in her eyes. She put a hand over her mouth, fighting to keep the tears in, but despite her best efforts they began to leak out.

"Something wrong?" Neuro asked, and the pure concern in his voice made the tears flow faster. She wished he would just insult her and smack her into the window like he used to; it was so much easier to deal with these feelings when he was like that.

"I...nothing. Just...no, nothing. I'm fine."

Neuro continued to stare at her, his expression enigmatic and unreadable. Yako felt ill. She had thought that Neuro's disappearance from her life was going to be permanent, and had thus been able to slowly bury her feelings deep within her heart, to a place where they couldn't escape. But now, seeing him again, now that she was older, more world-wise, had resurrected all those uncomfortable emotions that caused her to lie awake in bed for nights on end, wondering if he'd ever reappear back into her life.

And now, the knowledge that he had to leave for longer, for another vast period of time...well, it was breaking her heart.

So she made a decision.

--

"Neuro, can I do something to you?"

The demon looked apprehensive. "What exactly to you want to do?"

"Just something humans do; it won't hurt, and it will make me feel better."

Neuro rolled his eyes. "If you must," he replied, and Yako dimly recalled a time when he would have sent her flying through a wall for even daring to think about such a request.

"Thanks. Could...could you close your eyes?"

Neuro raised an eyebrow, but miraculously, he obeyed.

Yako leant forward, not really knowing why she doing what she was about to do, but maybe doing this would finally kill those painful emotions floating around in her mind. If she survived, that was.

When their lips met, Yako didn't really know what to think. There was no pain, which was a plus; knowing Neuro, his lips were likely to be radioactive. In fact, it actually felt extremely good; far better than the other small number of men she had kissed.

It felt right, which made her feel so, so wrong.

The detective quickly broke the kiss, falling back into her seat. "Oh, god..." she murmured, covering her mouth. 'That just made it worse.' She leant forward, leaning on her knees, breathing deeply, struggling to control herself.

"Do you feel better, earthworm?" Neuro asked.

"...not really." Yako said softly, still staring at the floor. Suddenly, Neuro grabbed her by the back of her head, hand wrapped tightly in her hair, yanking her head upward. Thinking he was going to punish her for the (stupid, stupid, what-was-I-thinking-this-isn't-some-shoujo-manga) kiss, Yako immediately winced. Their faces drew close, and she squeezed her eyes shut. When she finally realised he was kissing her, her hands had somehow already ended up in his hair of their own accord, and she was somehow subconsciously kissing him back.

Praying that her tongue was not about to be burnt off, the teenager deepened the embrace, pushing herself against her partner, trying to express physically what she could not do with words, and when she felt his hand on her waist, a happiness that she didn't know existed welled within her, to the point where she didn't think such a feeling was possible.

Neuro was the one to break the kiss, but he didn't move the hand from her waist.

"What about now?" he asked, grinning his demonic grin.

"A little," she replied softly, smiling weakly. "I didn't know demons kissed."

"Well, it's a little bit different in hell, you see-"

"On second thought, pretend I didn't say anything."

Neuro just grinned.

--

"I have something to admit to you, maggot." he said, his arm still around her waist.

"And what's that?" Yako replied, resting her head on his shoulder.

"I might have been...how do you inferior creatures say it...pulling your leg, a little."

Yako lifted her head back up. "What?"

"I slightly exaggerated the time period that I need to wait between my visits to your world."

"..define 'slightly exaggerated'."

"Well in reality, I really only need a week or so of your time in between trips."

Yako blinked. "Hang on. So...these past three years..."

Neuro's best screensaver face appeared. "...were all a test of your loyalty. Congratulations; you actually managed to evolve enough to pass. I've trained you well."

Yako just stared, utterly, completely gobsmacked. She couldn't have stopped her jaw hanging open if she tried.

"Don't look so indignant. What else did you really expect?"

"So all this time, whenever I've been sitting alone, depressed and lonely because I missed you, you've been watching me through the ceiling, laughing."

"That's...actually fairly accurate." Neuro could not stop grinning. "I needed to see if you could function without me guiding you, if you could evolve yourself of your own accord. Which you have. So you've passed the test."

Yako slapped him.

Neuro blinked, before turning back to Yako. The detective had never looked so angry.

"You still don't understand anything!" she hissed, unable to stop the tears trickling down her cheeks. "Do you have any idea how much it hurt to say goodbye to you? To have you just leave? Like the year we spent together meant nothing? You changed my life, Neuro, and then you just left, and I tried to understand because you had to go, because they needed you, but now you tell me it was all just a game to you? Just another stupid test? Are you ever going to be straight with me?"

Yako was waiting for the pain to come, for him to retaliate, to punish her for her insolence.

"Well?" she asked, her voice breaking, angrily wiping the tears from her face. "Aren't you going to hit me back?"

But it never came.

Neuro was staring at her, his expression unreadable once again.

"Maybe you're the one who needs to evolve, Neuro." Yako said. "Have you ever considered that?"

"My absence." he said suddenly, and Yako couldn't stop herself jumping slightly. "Did it really cause you that much pain?"

Yako turned her attention back to her shoes. "...Yes, Neuro." she said softly. "It did."

He fell silent for a moment, before saying "Do you remember when we split up, before Sicks was defeated?"

Yako could remember. It was still a painful time to recall. "Yes, I do."

"When you left, I didn't know how to react. It was odd; I'm not accustomed to....feeling anything like what you humans do towards each other. Demons just don't do that. But somehow, when you were gone, I felt something towards you, and it left me empty, and I didn't know how to cope with that, because I didn't understand what it was. But now, I think I do. Is that...the feeling you felt when I left?"

Listening to him speak so frankly and yet with such obvious difficulty made something inside Yako stir. "Yes. It was."

Neuro closed his eyes. "Then I am sorry for forcing you to feel that horrible emptiness that I so despised."

Yako blinked. Neuro was...apologizing to her?

"I hope you can forgive me...Yako."

They sat in silence for a few moments, before Yako suddenly took his head in her hands and pressed a kiss against the demons lips. Neuro's eyes snapped open in surprise, meeting Yako's happy smile, her eyes bright.

"Congratulations," she said. "You've evolved."

And Neuro couldn't restrain a grin.

--

They sat there for a little bit longer, Yako again resting her head on Neuro's shoulder, with the demon's hand on her waist. Then Neuro decided to break the silence.

"I just have one question for you, Yako."

"Yes?"

"Are you quite sure you don't want my nuts?"

END

Epilogue:

"Hey Katsuragi! You might wanna take a look at this!"

Yako looked up at Higuchi, who had an odd look on his face, raised an eyebrow, and took the proffered magazine.

She then screamed at the picture splashed across the front cover, featuring her and Neuro on the plane, locked in an embrace.

"SUPER SLEUTH KATSURAGI YAKO'S PASSIONATE PLANE TRIP!"