Hearing the pointed undertone in Rias's words, Ren Kuroda paused for a moment, clearly caught off guard. Then he looked at her and replied with a teasing smile.
"Rias, you look like someone who trains regularly. Even if you skipped your warm-up once or twice, with your physical condition, you wouldn't pull a muscle that easily, right?"
Rias had been subtly implying that Ren wasn't an ordinary teacher. Ren, in turn, shot back that she wasn't an ordinary high school girl either.
A normal girl might strain something from skipping warm-ups—but Ren didn't believe for a second that Rias belonged in that category.
If a high-ranking devil could get injured just from not stretching before a run, then the whole concept of devils would be a joke.
"If you're a teacher, then helping your students when they need it is only natural, isn't it?" Rias said calmly. "That's exactly why Ms. Shinohara asked you to substitute today, right?"
Setting aside the fact that one was a devil and the other a half-yokai, there was nothing wrong with what she said. In the end, Ren stepped forward and helped her with her stretches.
"You don't seem to have any guard up around me at all, Rias. Aren't you worried I might try something?" Ren asked, puzzled.
Rias bent forward without hesitation in front of him, her posture completely unreserved. As she stretched, her ample chest pressed against his thigh, forming an eye-catching curve that would've rattled most men.
"After what happened last night, I think I've gotten a basic grasp of your strength," Rias replied evenly. "If you really intended to harm us, Akeno and I probably wouldn't have walked away unharmed."
She paused slightly, her gaze sharpening.
"Besides… I'm more curious about people like you, Ren-sensei. Are there many humans like you? And what exactly is your purpose for coming to Kuoh Academy?"
After finishing their warm-up, the girls began jogging around the track under Ren's instructions.
To be honest, watching high school girls run was far more pleasing to the eye than watching boys sweat through endless laps. Ren quickly understood why the school separated male and female students during P.E.
Most of the girls had already fully matured, and Kuoh Academy's student body was notably high-quality. As their white gym uniforms clung to their bodies, damp with sweat…
Even someone as desensitized as Ren—who had seen his fair share of things—found himself struggling to keep his composure. For teenage boys bursting with hormones, it would be outright torture.
"So your reason for becoming a teacher here isn't just to admire the scenery, I assume?" Rias asked, arms crossed as she stood beside him. With fewer students nearby now, she could finally speak more freely.
"Well, becoming a teacher wasn't exactly part of my original plan," Ren admitted with a shrug. "But the main reason I came to Kuoh Academy… was because of you, Rias."
Caught completely off guard by such a direct statement, even the usually composed Rias couldn't help but blush deeply.
There was no denying that Ren's strength and appearance aligned well with her tastes—but she wasn't so easily swept away.
Besides, she didn't believe her reputation had spread far enough to reach outsiders.
The Gremory family held Duke-class status in the Underworld, and as its heir—combined with her possession of the Power of Destruction—Rias did have some fame. But that recognition was limited to the younger generation of devils. Veteran devils might only know that the Gremory house had a daughter like her—let alone people outside the Underworld.
"It seems you're quite skilled at flattering girls, Ren-sensei," Rias said, regaining her composure. "But I'd prefer to hear your real reason."
Ren immediately realized she had misunderstood and sighed lightly.
"I really did come here because of you, Rias. More precisely, I came because of the devils at Kuoh Academy—and you happen to be one of them. So technically, I'm not wrong in saying I came for you."
"For the devils here?" Rias raised an eyebrow. "And why exactly are you looking for devils?"
Hearing that his goal wasn't specifically her, Rias realized her earlier assumption had been off.
"I want to pick a fight with the so-called Four Great Satans," Ren said casually. "Actually, not just them—angels, gods… anyone strong enough. I want to test myself against them."
"You want to challenge the Devil Kings…?" For the first time, Rias completely lost her composure.
What were Devil Kings?
They weren't just symbols of overwhelming power—they were the rulers of the entire Underworld, beings who stood at the absolute pinnacle of all devils.
And yet the man standing before her spoke of defeating them as if he were discussing something trivial—and he was saying it right in front of a devil, no less.
While Rias was still reeling from the shock, Ren continued talking as if nothing was out of the ordinary.
He even mentioned that, given her apparent status in the Underworld, she might be able to contact a Devil King—and asked if she could arrange a meeting so they could "have a proper fight somewhere."
"…Why?" Rias finally asked, forcing herself to steady her voice. "Why would you risk your life to challenge the Devil Kings? There must be a reason."
At this point, she understood why Ren had been searching for devils in the first place—he was essentially looking for someone to deliver a challenge letter.
After all, devils rarely left the Underworld, and ordinary humans had no way of entering it. So Ren had been trying to find a devil who could communicate with the higher-ups.
"Well, it's not like I don't have a reason," Ren replied with a grin. "I want to become stronger. And for that, I need opponents strong enough to push me."
There were two main reasons Ren sought out battles with gods and devils.
The first was his current main quest:
Main Quest 1: "One Who Makes Gods and Demons Tremble"Objective: Defeat or draw against three beings at the level of a Devil King, a god, or a Dragon King.Reward: 50,000 Yokai Reputation Points
Main Quest 2: "Forge the Blade into a Divine Artifact"Objective: Evolve the semi-awakened Kamui into a true Sacred Gear.Conditions:
Absorb two or more Sacred Gears
Be stained with the blood of a god, Devil King, or Dragon KingReward: Complete awakening of the blade spirit
These were the two primary missions that had brought Ren into this world. And no matter which one he pursued, he would inevitably have to stand against gods and demons.
Beyond that, in his original world, he had learned from Izanami how to control the power known as "All the World's Evil."
But training that power required an opponent of equal caliber.
And this world—with its abundance of gods, devils, and overwhelming forces—was the perfect place.
Naturally, Ren Kuroda couldn't wait to throw himself into battle.