Disclaimer (applies for all chapters): Neither Alex Rider nor Detective Conan/Magic Kaito belongs to me.

A/N: This is a crossover between the Alex Rider series by Anthony Horowitz and Detective Conan/Magic Kaito by Gosho Aoyama (with possibly more to come), and the second part of a series. If you haven't read Viper's Den, I strongly suggest reading that first.

With the upcoming Never Say Die, this is now AU for Alex Rider after Scorpia Rising. For DCMK I'd say we're past the Mystery Train and Scarlet Showdown arcs.

Chapter 1: Introduction to Japanese

Alex's first sight of Japan came through a break in the clouds as they approached the islands, brown and green against the dark blue Pacific Ocean.

"There's Hokkaido up in the north," Saguru pointed out through the window by their spacious business class seats. "Honshu's the main island, with Tokyo in the middle. Shikoku and Kyushu are the lower parts."

Alex repeated the names, then grimaced as he instinctively put stress on the syllables. It was hard not to, after years of lilting Romance languages. "I am not going to be able to understand anything." Alex had thought he was good at languages, but Japanese was a completely different beast from French or Spanish, and he was frustrated at how long it took him to get used to the new writing system and sentence structures.

"You picked up hiragana and katakana quickly."

"And fell flat on my face when I tried to learn kanji. What kind of writing system needs three different alphabets?"

"Syllabaries," Saguru corrected. "Everyone has trouble with kanji—even mine is not as good as I would like, after spending so much time abroad. The major streets signs in Tokyo were recently changed to have English added. Koizumi-kun and I can both translate whenever we're together as well."

"Speaking of Akako…your mom decided to talk to me about her." Or rather, Saguru's mother had cornered Alex while her son was away making last minute preparations for their trip. Dr. Elizabeth Hakuba had maneuvered him into sitting down for tea. Then with a deadly combination of precise decorum and genuine motherly concern she had proceeded to squeeze him like a sponge for information about her son. "If she ever gets bored running the company, I know some people who would love to have her on as an interrogator."

"Ah. I'm not surprised," Saguru sighed. "I was hoping to properly introduce Koizumi-kun to Mother later, but they ran into each other at the mansion while you were out."

"And?"

"Mutual dislike on sight."

Alex whistled. "God, I wish I could have seen that."

"Trust me, you do not. It was a highly uncomfortable experience for any bystanders in the vicinity."

Alex tried to picture the Hakubas' unexpectedly formidable matriarch and Akako facing off, and silently wished Saguru luck.

Their plane soon began its landing on the small man-made peninsula of Haneda Airport, and Alex abandoned his probing into Saguru's romantic and familial woes and turned to peppering the other teen with questions about his surroundings instead. After landing, they were quickly picked up by the Hakubas' housekeeper, a tall older woman with curled iron grey hair who kept on calling Alex "Mr. Rider" despite his best efforts.

"Baaya, has news of the KID's new note become public knowledge here yet?" Saguru asked her once the three of them were sitting privately in the family Lamborghini and on the hour-long drive to the Hakuba family mansion. It hadn't when they left, but a lot could happen in the twelve hours it took to fly from London to Tokyo.

Baaya shook her head, raising tiny clinking sounds from the thin chain on her round glasses. "Inspector Nakamori is planning to hold a press conference tonight, now that they know what the target is."

Alex blinked. "The Inspector's already figured out the note?" He remembered the booby-trapped gift box they had received in London with its pristine white card, and the lines written in English upon it:

The pursuit of beauty is its own reward.
On the last nod of the bamboo staff,
I shall pass through water and fire
for the Selene blessed firstborn
of one who spun color from sand and rust
when she shines full.
—Kaitou KID

Reference to the full moon aside, Alex hadn't been able to make heads or tails of the note. After spending every spare moment before they left researching, Saguru finally cracked it while using Heathrow Airport's wifi before they boarded the plane and was so smug Alex had to ignore him during most of the flight.

"No, someone else did. Or rather, two someones." Baaya was driving and couldn't turn around, but she paused significantly. "Saguru-botchama, I believe you know them both. That little child who chases KID and his Osakan friend."

"You mean…"

"Yes. Apparently, both Edogawa Conan and Hattori Heiji also received heist notices."

Conan sneezed. So did Heiji. Thankfully, the corpse on the ground didn't join in.

"Bless you both," Police Detective Miwako Sato said from her much cleaner spot near the door.

Heiji had come to visit Conan in Tokyo for the KID heist ("Ya thief invited me, Kudo!"). The two had gone out to eat at a gyoza joint, but they had barely begun to dig into a plate of the piping hot, crispy-skinned dumplings when a woman's voice screamed and a dead body fell to the ground outside their window seat.

Heiji took note of the stiffness of the corpse and mentally estimated how long rigor mortis had set in, and from there, the approximate time of death. "An' here I thought the KID heist would be the only case I'd get involved with on this trip."

"Hattori-kun came up from Osaka for the heist?" Sato asked as she went through the dead man's pockets. "Though I suppose that's not too far. Apparently Superintendent Hakuba's son flew back all the way from England to attend this one."

Conan was surprised. "Hakuba Saguru came back to Japan?"

"That blond jerk?!" Heiji exclaimed at the same time.

But if Hakuba was here from England, Conan thought, then that means…he shook his head, and returned his focus to the dead body before him. He had a murder to solve; he would have to figure out the implications of the half-British detective returning to Tokyo afterwards.

One investigation, demonstration of the ingenious murder method (involving the use of fishing line, rubber bands and a trained hamster) and subsequent arrest later, Heiji and Conan moved to a new seat in the back. The long-cold gyoza had been replaced, and the grateful restaurant owner had given them a free plate of takoyaki as well for seeing through the frame-job on her son. Conan was still mulling over what Sato had told them as they reattacked their food.

"If Hakuba Saguru is here for the Kaitou KID heist, then it's almost definite that Alex Rider is also here with him," he said.

Heiji paused in his attempt to stuff three dumplings at once into his mouth. "Oose 'lex Rid'r?"

"Now there's a question. At first glance, he seems to be a teenager Hakuba's mother hired to accompany him during the summer."

Heiji laughed. "Hakuba's mom got 'im a babysitter?"

Conan told him what he knew from Ai about the kidnapping attempt she, Hakuba, and the teen named Alex Rider had foiled together, and then the poisoning case the three also became embroiled in in England. "Haibara asked me to investigate Alex Rider after she met them again in Lymstock. I told her there was hardly anything to go on."

"But ya found something."

"Yes." They were in a deserted corner of the restaurant and the background chatter was loud enough to cover their conversation, but Conan scanned the room and lowered his voice anyways.

"I had little idea where to begin at first. All I had to go on was that this unusually skilled teenager, who despite being a complete stranger to Hakuba Saguru, was suddenly accompanying him everywhere right after a failed kidnapping attempt on the latter. Now the two of them could have suddenly hit it off—"

"With Hakuba? Ya gotta be kiddin'." Heiji snorted. "So ya thought he was hired as a bodyguard?"

"That would make sense, given the kidnapping. But then you would have to wonder why Hakuba's mother—by all accounts a shrewd businesswoman, proper English lady and nobody's fool—would accept a sixteen year old as the protector of her only son and heir."

"A teenager her son's age would stick out less than an adult bodyguard? If he can fight as well as ya said, it wouldn't be that bad a trade-off. An' he'd have the advantage of bein' underestimated due to his age."

"That still leaves the question of where he learned to fight like that. And there's another thing." Conan paused and scanned the restaurant again under the guise of sipping his green tea. "Haibara is positive that one of Them was at both the kidnapping and at the summation gathering in Lymstock where Hakuba revealed the killers. She got a text message with a reference to her code name at the kidnapping, and in Lymstock…Haibara went there in the first place because a biochemist named Simon Perréal had some research that could be helpful in deriving an antidote to the Apotoxin. But she felt the presence of one of Them during Hakuba's talk, and there was an unexplained fire in Perréal's lab immediately afterwards. She thinks…she thinks it might have been Vermouth."

Heiji considered it. "Maybe They were there to destroy or steal Perréal's research?"

"Theft is more likely. Haibara's pretty sure Perréal kept secure backups of his work, but any traces of a break in would have been covered by the fire." Ai had made her own copy of Perréal's work well before then; ever since her return she'd spent every waking moment outside of school down in her lab, trying to incorporate his biochemistry research into her own attempts at creating a cure for the Apotoxin.

Heiji speared a takoyaki ball with his chopsticks and chewed it thoughtfully. "Ah. So ya were also wonderin' if this Alex Rider has anything to do with the Syndicate."

"Haibara said that she was positive Rider isn't malicious, but she does think he's dangerous."

"Not evil, but dangerous, is an unexpectedly skilled fighter an' conveniently appears at both instances where They showed up in England…" Heiji whistled. "Ya think he's another undercover agent like Jodie-sōsakan? But he's what, sixteen?"

"We're around that age," Conan reminded him. "It's just a guess. I've asked Jodie-sensei to tell me if she knows anything, but it'll probably take some time for her to get back to me."

"But he'll be there at the heist." Heiji grinned. "Saturday evenin' is gonna be very interestin'."

The next morning, Alex accompanied Saguru on his morning walk to Ekoda High.

"I can't believe you're going to school on a Friday," Alex said, stifling a yawn. Both boys had opted to stay up the entire night to adjust to the time difference faster, and Alex felt lightheaded from both the jet lag and the lack of sleep. Saguru looked reasonably awake, the effect of pouring two cups of black coffee down his throat at breakfast.

"Exams are starting soon; I don't want to miss any more of my classes if at all possible," Saguru said. They stopped outside the school gates, and Saguru straightened invisible wrinkles from his school uniform. "I told Koizumi-kun I'd wait for her."

"Okaerinasai Hakuba-kun! Koko ni anata no tomodachi wa dare desu ka?" A cheerful greeting came from a schoolgirl who was approaching them. She was accompanied by an energetic boy with unruly black hair who grinned wildly upon seeing Saguru. He began talking rapidly in Japanese while gesturing between Alex and Saguru, blue eyes alight with mischief, until the girl grew frustrated and tried to to whack him with a cry of "Bakaito!"

"She's Nakamori Aoko, and the idiot she's chasing around is Kuroba Kaito," Saguru told Alex. "They're both in my class."

Alex watched as Kaito bounced around the school entrance with Aoko in hot pursuit. Other students in uniform passed through the gates with barely a glance, as if the sight of one of their classmates performing handsprings and throwing live doves into the air while another chased him around with a broom was an everyday occurrence. "Is this normal?"

"With these two, yes." Saguru watched the two with something like fondness under his normal reserve. "Aoko-kun is normally very sweet-tempered, but Kuroba-kun can drive a saint to violence."

As if summoned by his name, the teenager in question abruptly cartwheeled to a stop in front of Alex. He clapped his hands together with a wide smile, and a puff of smoke appeared with a crack over his palms.

Alex reacted without thinking. In one move he snagged both of Kuroba's wrists together and yanked so that the boy's arms and whatever he was holding was aimed at the ground, out of the way of any bystanders. At the same time he moved closer in preparation for a throw, but the other boy shifted in parallel so that they stood side by side instead.

Kaito's wrists tensed momentarily inside Alex's grasp as if he was about to twist out of his hold before relaxing again. His smile remained pinned in place. It was only then that Alex registered what he was holding: a giant bouquet of roses, somehow dyed in the pattern of the Union Jack.

"Like I said, enough to try a saint," Saguru said casually. "Kuroba is an amateur magician, class clown and devoted Kaitou KID fan." There was an edge in the way Hakuba said the last bit which Alex didn't know how to interpret. "Aoko-kun, Kuroba, my friend here is Alex Rider. He's staying with me for the summer," Saguru continued, then he repeated what he said in Japanese.

"It's nice to meet you!" Aoko said in English. She bowed formally. "Sorry about Kaito. He is…" The extent of her foreign vocabulary seemed to fail her when it came to describing her friend, so she made a few annoyed gestures instead.

"Yes, sorry about that," Kuroba echoed. His English was much more confident, even if his accent was strong. "Do you not like roses? I prepared them for Hakuba, but I got excited. Did you two just return?"

"I like them fine, just not in smoke bombs," Alex said. Then he caught himself; Saguru's classmate was just a prankster. Just a prankster, and maybe a bit of a jerk, but not a threat.

"We flew in yesterday afternoon," Saguru said in response to Kaito's other question.

"Has he shown you around Tokyo at all?"

"A little. I've seen the Skytree, and the Ameyayokocho Street Market," Alex said in his best attempt at Japanese. At his request Saguru had spent the previous evening without using any English. Alex wanted to become as proficient in Japanese as he could, and immersion was the fastest way to achieve that.

"Oh yes, my father said you came to talk," Aoko said.

"Aoko-kun's father is Inspector Nakamori, who leads the Kaitou KID Task Force," Saguru explained.

"With you and the other tanteis there, I'm sure you guys will catch that stupid thief this time!"

Kaito scoffed. "Sorry Aoko-kun, but Kaitou KID wouldn't be caught that easily."

"My, aren't we confident," a knowingly amused and very familiar voice said. Alex turned to see Koizumi Akako, glamorous even in uniform as she slipped up beside Saguru and leaned suggestively against his shoulder. "Good morning, Saguru-kun. And to you as well, Alex—" Alex nodded back in greeting "—I hope you're enjoying Japan. Nakamori-kun, Kuroba-kun."

Aoko's eyes widened in delight. Kaito's eyes widened for very different reasons.

"Akako-chan! Are you two dating now?" Aoko asked.

Saguru looked nervous, and then he determinedly slipped Akako's free hand into his. "Yes." Akako glanced at him, but didn't object or move her hand away as congratulations burst out of Aoko in Japanese.

Kaito, Alex noted with interest, looked absolutely horrified.

"When did this happen?" The boy demanded in Japanese.

"In England. We—" Saguru began to answer, but then the school bell rang. "We had better go in before we're late. I'll see you after school," he said to Alex. "You will be fine exploring Tokyo by yourself?"

"I promise not to destroy the city my second day here," Alex said, and waved as they headed inside.

The break bell rang at Teitan High School, and Suzuki Sonoko immediately moved over to her best friend's desk. "Ran, let's go grab the spot under the sakura tree before it gets taken!"

The other girl didn't move from her position, her head propped up on one arm pensively. "Ran!" Sonoko leaned down to lightly link her own arm through her friend's, putting their heads side-by-side. "What are you daydreaming about?"

Ran's eyes refocused on Sonoko, and she smiled fondly. "I was just thinking about all of this—" she gestured at the classroom around them, with their classmates slowing flowing out. "—and how we only have a year left."

"Ya, Mouri Ran, you're making us sound old."

"It's not that long! Kasama-kun's planning to use the entire year to prep for the university entrance exams, and she's not the only one either. Have you thought at all about what you want to do afterwards?"

Sonoko shrugged. "Go to university here or abroad, most likely. I'm not aiming for anywhere like Todai. Oh, are you worried about the tests? But your grades are great, you'll do fine."

"But I'm not attending cram school or studying a lot outside class like Takashima-kun and Kasama-kun and the others." Ran frowned. "And I'm not even certain where I want to go either. Spending all that effort studying for the tests would be a waste if I ended up deciding to go to a technical school or something."

"Study abroad then! There are scholarships and exchange programs that aren't that expensive. We can go together and see the world."

"That would be nice. But I have people here that…" Ran suddenly seemed to come back to herself. "Look at the time! If you still want that spot, Sonoko, we'd better run."

Sonoko frowned as Ran stood up and headed towards the door, beckoning her to follow. Ran didn't say his name, but Sonoko was sure that a certain absentee Holmes-nerd had been in her mind. Sonoko had tried to be more accepting of the bond between Ran and Shinichi, because she knew how much Ran cared and guessed that Shinichi felt the same. But worries still stirred up in her mind.

Kudo Shinichi had been gone doing who knows what for almost two years now. How much longer would Ran keep on waiting for him? Until they were done high school? Even longer? What would she sacrifice to ensure that she would always be ready in case he returned? Would she try to keep herself unchanging, faithfully frozen in a cyclical limbo of anticipation and disappointment?

It was by no means the first time Sonoko had wondered what the hell was taking Kudo-kun so long to come back to Ran, but it was the first that she resolved to Do Something about it.

If the detective geek was hiding on purpose for some reason…well, then, Sonoko would have to fight fire with fire.

At the same time in another part of Tokyo, the break bell was also ringing at Ekoda High.

For once, Kaito didn't protest when Akako sprang upon him and dragged him up to the school's roof. At least she had waited until Hakuba had left to go talk to the teacher about his missed schoolwork first. The roof was off limits to students, but neither of them cared about the rules, and the door's lock was laughably easy to pick. He locked it again behind him to ensure privacy, then walked over to the edge of the roof where Akako stood, her red hair moving in the breeze.

"You need to know something about the heist tomorrow," she began, but Kaito stopped her.

"We need to talk about Hakuba first," he said. "Akako, if you're using your magic on him, stop it."

Akako huffed. "I'm not. What gave you the idea—"

"The two of you barely even talked to each other before. Then you both go away and suddenly you're dating?" Kaito narrowed his eyes, though the smiling curve of his mouth didn't change. "I didn't know England was such a romantic country. What happened there anyways?"

"One of my cousins there was murdered, and he helped find the killer." Also I was poisoned and almost died, and he stopped me from killing the culprit, she thought but didn't say. Somehow Akako didn't think that was how most relationships began. "We…we saw a lot of each other, during the investigation."

"Oh." The look in Kaito's eyes softened a little. "But still Akako, even if Hakuba comforted you then or you liked how he solved the case, you can't take advantage of someone like that—"

"I am not using magic to bewitch him!" Akako snapped. Her throat felt raw. "Do you want me to swear a blood oath on it?" And to think that she came up here to try to help him! She was one step away from trying to hex Kaito into next week. "Is it so hard to believe that someone could like me without being glamoured into it?"

Kaito almost gawked at her, his usual jester's smile gone. "Kami save us all, you actually do like Mr. Tweed Wonder." He blinked, and assessed her as if she had sprouted a second head. "Though I suppose I should warn you that if you ever hurt him…" Hakuba Saguru may be an obnoxious Holmes-obsessed twat, but he was one of his tanteis, damn it.

"Oh for Lucifer's sakes, you're almost as bad as his mother." Akako rolled her eyes, but at least she no longer looked like she wanted to claw his out. "Do you want to hear my information or not?"

"Ah, what did Miss Witch see in her magic mirror this time?"

Akako ignored his teasing tone and went on. "Events are…more unstable than usual." She was reluctant to admit that her powers were still on the mend from her poisoning and weaker than she would have liked. "There are two paths. Kaitou KID fails and is captured in one, either by your tanteis or by Alex Rider. And in the other…a black shadow awaits, and the white thief is shot down from the sky."

Most of that wasn't very unexpected. "Alex Rider?"

"He used to be a secret agent for MI6." Kaito's Poker Face stayed in place, but the pause was revealing enough. "You didn't know?"

He whistled. "That does explain his reflexes earlier. Hakuba must have been a busy bee in England. A murder, a girlfriend and a spy all in one trip?"

"Hakuba-kun didn't hire Alex; his mother did. As protection, I think." Akako's gaze grew distant. "Alex met someone from his past while we were in Lymstock, someone he will meet again…" She blinked and came back to herself. "Alex didn't work for MI6 willingly, and he's not working for them anymore, but he may still decide to use his skills to catch KID. So you shouldn't go to this heist. There are too many opponents."

Kaito grinned. "I, Miss Witch, am only attending as an ardent fan of KID. Tanteis, shadows and a young James Bond? How can you ask Kaitou KID to miss a show like that?"