The story takes place after the correction of the Subspecies Singularity, Agartha, several months later, on a sweltering summer day. Upon reaching summer in Chaldea, it was only natural to summon Servants to enjoy the season.
"Umu! Umu!"
The young tyrant emperor laughed heartily as she pushed open the door to the Master's room and declared, "According to the calendar, it's June! Finally, it's here! It has finally arrived!"
"Indeed, even the digital age's shut-ins have started to move about, and this is the season when people impulsively decide to embark on trips!"
The fox-eared girl accompanying her chuckled.
"Yes, that's right! It's finally Golden Week!"
Bursting into laughter, the tyrant emperor opened the door, only to see a tall, black-haired young man who looked remarkably similar to herself. More importantly, he was holding a set of cards in his hand, accompanied by two girls sitting on the bed.
Without showing any panic from being caught slacking off, the young man casually made the cards in his hand vanish with a flick of his wrist and greeted them with a smile, "Good afternoon!"
"Hmm?"
The emperor, Nero, strode forward with large steps and suspiciously examined the knight in front of her. However, she soon broke into a wide smile and said, "Umu! Umu! Not bad! Would you like to become my knight? Stop following that outdated King of Knights!"
"It's not exactly the season for a career change," replied Alaric, as he clapped his hands and stood up. "But can I do it as a side job?"
"Hmm? You're quite greedy!"
Nero clapped him on the shoulder, laughing, before turning to look at Fujimaru Ritsuka and Mash, who were sitting cross-legged on the bed. She exclaimed, "In conclusion, let's go to the beach, Master! I've been looking forward to it since last year, and this year I absolutely must wear a swimsuit!"
"Oh dear, Saber, you don't have a swimsuit yet?"
Feigning shock, the fox-eared girl, Tamamo-no-Mae, smiled mischievously as if wagging her tail. "I can't believe the unstoppable Emperor only has one outfit. Could it be that you're not confident in your figure?"
"Fool! Last time, I was considerate enough to let other Servants have the spotlight. After all, Mordred's armor was quite intense," Nero declared confidently. "But that kind of kindness is a thing of the past. This year, I'm going all out! My swimsuit will be utterly breathtaking!
You can think of the next week as a demo version, or let's just say I can't wait for summer to come! I heard you all spent a month on a southern island back in 2017. Well, from now until summer, I'm going to enjoy it to the fullest!"
"That wasn't exactly a pleasant experience!" protested Tamamo-no-Mae. "I'm already sick of drifting around in a swimsuit!"
"True," Fujimaru Ritsuka chuckled, folding her arms as if recalling something. "That did happen."
"Summer, huh? Sounds nice," Alaric mused, stroking his chin. "I used to go on vacations back in the day."
Before the conversation could continue, a broadcast interrupted the mood.
["Testing, testing. Attention all staff currently on standby in their rooms. A scheduled contact from the offshore oil rig base, Seraphix, has been received. You can now use email or video calls to communicate.]
[If any staff members have friends stationed at Seraphix, please make your way to the control room when you have the time. This communication window is expected to last half a day. The next contact will be three months later. If you have any urgent matters—"]
The announcement by Da Vinci, who had to personally oversee control room duties due to Mash being temporarily unavailable, was cut short by Nero's confusion.
"Hmm? What's Seraphix?"
She turned to Fujimaru Ritsuka and Mash on the bed, seeking answers.
"Eh? I don't know," Fujimaru Ritsuka admitted, turning to Mash for clarification. Mash, always a reliable source of information, smiled and explained:
"It's one of Chaldea's departments. Seraphix is an offshore oil rig base located in the North Sea. It belongs to the Animusphere family and is a semi-submersible platform.
More than a hundred staff members work there day and night. Although it's far from Chaldea's main facility, it's considered an important source of funding for Chaldea's operations."
Mash hesitated slightly before adding, "I've never been there myself. I only know about it from the records."
"Then let's go check it out!"
Spurred by curiosity, Fujimaru Ritsuka pulled Mash along, heading to the control room. When Da Vinci learned of their arrival, she laughed and said, "I've never been to Seraphix either. Or rather, only the staff who were present during Chaldea's founding knew about it. Unfortunately, most of them lost their lives due to Lev's bomb incident.
The staff currently in contact with Seraphix are what you'd call 'communication friends,' having built connections through years of correspondence."
"That side endures harsh conditions at sea, while we're working in a snowbound mountain. Even communication can bring new topics of conversation, and that's something to be happy about," Mash noted with a smile.
At that moment, a Chaldea staff member opened an external communication line, connecting to Seraphix's video channel. However, instead of the expected image of Sheba, nothing changed, leaving everyone puzzled.
Before Da Vinci could determine if it was a mechanical failure, a noise came through, delivering a chilling message:
["Help… big… please—"]
"Turn up the volume! I heard something!" Mash urged, her expression serious.
As the staff increased the volume, the desperate plea became clearer:
["I—I don't know why this is happening… Everyone has disappeared… Please, help… Is anyone there?
Everyone… everyone has been converted into data…"]
The desperate cry ended abruptly.
"Communication with Seraphix has been cut off! No response!"
The staff member in charge of the connection reported urgently.
"Use Chaldeas to observe Seraphix in 2018!" Da Vinci commanded as the acting director. "Even if we can't hear anything, we can analyze light patterns to determine if there's been a fire, an accident, or something else!"
"No observation possible! Seraphix doesn't exist! There's nothing there—no abnormalities on the surface or underwater, and no singularity detected!"
"The source of the earlier communication is untraceable—it's from an unknown realm beyond our perception!"
A flurry of emergency reports followed, plunging Chaldea's control room into chaos.
Alaric observed Chaldeas in silence, while Fujimaru Ritsuka and Mash wore grim expressions. Then, a mysterious voice echoed:
["Ah~ Testing, testing. Can you hear me? Is the microphone sensitivity okay? Perfect? Wonderful! Chaldea, are you listening?"]
The playful voice continued:
["Is everyone enjoying their private time? Or are you busy working? Maybe out on a mission?]
[If you're in a crowded office or on the subway, I suggest you turn off your phone's ringtone.]
[That way, you can avoid social death before your life is stolen! Because up next is—BB Channel!"]
With the sound of bizarre music, the screen changed to a pink-colored world, and a girl appeared.
["Humans~~ Are you still standing there dumbfounded~?"]
The mysterious girl, who seemed all too familiar to some, smiled mischievously:
["Or are you panicking like ants under attack~? It must be the latter, right~!]
[Ah, no matter how many millennia pass, you humans never improve! Even the evil BB herself can't help but pity you!]
[But don't get me wrong—it's not out of kindness, but embarrassment on your behalf!"]
Following her self-introduction as BB, the illegal upper-level AI, the already chaotic Chaldea plunged even deeper into turmoil.
"What's going on? Where's this communication coming from? Communications team, what are you doing?!"
The staff frantically tried to explain:
"We have no control over this! It's a completely different communication method from our systems!
The firewall has been breached! The Spirit Origin storage is locked! All external communications have been severed—"
"Chaldea's control has been completely taken over! What is this? Could it be some kind of super A-rank magus?!"
For the first time, Chaldea's staff faced a scenario they couldn't handle, and the question was answered by none other than BB herself:
["Unfortunately, no. I'm neither a magus nor a Master.]
[This broadcast is brought to you by none other than me, the Moon's Ruler—your beloved illegal upper-level AI, BB!"]