Koori Ui himself had once been the top graduate of the Academy, and was the only member of Squad Zero who had actually climbed the ranks through the proper Academy system.
A genius among pure humans—at just 24 years old, he was already an Associate Special Class, and would soon be promoted to Special Class.
"Because of the labyrinth's nature, the terrain heavily favors ghouls. They could ambush you at any moment. We'll protect you as much as possible, but don't let your guard down."
Koori Ui continued his warnings to Byakuya and the others.
"Understood."
Byakuya and the group nodded in acknowledgment.
From there, they ventured deeper into the underground labyrinth.
The shallow levels rarely had ghoul encounters. CCG investigators had explored Ward 24 countless times, especially with Arima—the "Undefeated Reaper"—leading Squad Zero on regular extermination missions here.
The CCG even used Ward 24 as a training ground for newcomers. Most students completed their internships here, led by senior investigators ranked First Class or higher.
"Senior investigators" referred to First Class, Associate Special Class, and Special Class ranks, while Rank 3, Rank 2, and Rank 1 were considered "junior investigators."
With investigators coming and going almost daily, few ghouls dared linger in the upper levels.
The atmosphere started out relatively relaxed, without much tension.
Shio Ihei even came over to chat with Byakuya. "Let me introduce myself properly—I'm Ihei Shio."
Shio wore a friendly, adorable smile. His personality was cheerful and outgoing, innocent like a child.
Well, Shio was a child. But if you converted his age to a normal human lifespan, he'd be at least 20.
Half-humans not only possessed far superior physical abilities, but matured much faster than normal humans. Their metabolisms were also extremely rapid—probably why their lifespans were so short.
"Nice to meet you. Though... how should I address you?"
Byakuya suddenly realized he wasn't sure what to call Shio.
Given Shio's young age, "Ihei-san" would sound strange. The original story hadn't mentioned Shio's investigator rank either, otherwise "First Class Ihei" or "Rank 1 Ihei" would be the proper form.
"That's easy—just call me Shio."
Shio said with a grin.
"Alright, Shio it is then."
Byakuya found Shio remarkably easy to get along with.
Sure, it was a shame such a cute face belonged to a boy—but then again, weren't cute boys even better?
That was a joke, of course. Seriously speaking, befriending this adorable yet powerful young prodigy could only be beneficial.
Despite being the youngest, Shio had actually eliminated the most ghouls among the "Squad Zero Trio." Whether or not he was the strongest of the three, he was certainly far beyond ordinary investigators.
The Squad Zero Trio (ages shown are from three years after the current timeline).
[Ding! Host has become friends with Ihei Shio. Reward: 2 Fusion Points!]
After just a brief conversation, Byakuya had easily befriended Shio.
Rikai Souzu was the quiet type, and Yusa Arima had a reserved, introverted personality—neither would initiate small talk with someone they'd just met.
Just then, Arima suddenly raised his hand, signaling everyone to stop.
They all halted immediately.
"Ghouls ahead..." Arima said, his tone flat.
But he showed no intention of engaging. The white briefcase in his hand—the specialized container for Quinques—remained closed.
Byakuya had already spotted the ghoul silhouettes lurking in the darkness ahead. He counted three.
Koori Ui immediately addressed the interns: "Those ghouls are yours to handle. Pair up and work in teams. We'll intervene if anything goes wrong."
CCG protocol typically paired senior investigators with junior ones—for example, Rank 1 Investigator Koutarou Amon was partnered with First Class Kureo Mado.
This exercise was meant to help newcomers adapt to coordinating with partners in combat.
Kurona would obviously pair with Nashiro. The two boys were more familiar with each other and teamed up as well.
That left Byakuya and Suzuya—they had no other choice.
Suzuya hadn't expected anyone to willingly partner with him, so he'd been preparing to go in alone.
But then Byakuya spoke up: "Suzuya-kun, we're partners now. When we engage, I'll leave that one's back to you."
As he spoke, he pointed at the ghoul radiating the most hostility toward them.
Suzuya's expression flickered with surprise, but he quickly recovered. A somewhat feral grin spread across his face. "Got it."
Combat seemed to be when he came most alive.
With Suzuya's acknowledgment, Byakuya launched the first attack. His explosive speed was startling—a gift from Madara's taijutsu.
Having locked onto their target, Byakuya and Suzuya charged forward. The Yasuhisa sisters, not wanting to fall behind, engaged another ghoul. The third was left to the two boys.
Arima and the others observed from the sidelines. If any ghoul proved too strong for the interns, or if danger arose, they would step in.
Roughly speaking, interns were only assigned B-rated ghouls.
The CCG's threat classification system rated any ghoul capable of manifesting a kagune as at least B-rated. Conversely, ghouls below B-rated couldn't use their kagune.
Weaker ghouls wouldn't provide meaningful training, while stronger ones were too dangerous. B-rated was the sweet spot.
"He's fast. Are the newcomers this time really this good?"
Byakuya's initial burst of speed had already impressed Koori Ui.
They'd supervised several batches of interns, but Byakuya was the first to give him this sense of astonishment.