They lost track of time while continuing to argue about magic, theory, and power control, but no matter how much they discussed it, they couldn't reach a definitive conclusion.
Arthur possessed sharp analytical talent and carried the equivalent of an entire magical library within his mind, yet even with all that knowledge, he still needed time to properly digest and adapt to it. Theory alone wasn't enough; experience was the real teacher.
Rias, on the other hand, had never been particularly interested in magic theory. Her power had always come naturally to her, so her understanding remained mostly intuitive and somewhat superficial.
Despite that, Arthur still gained several valuable insights from their discussion. When he returned home, he planned to carefully sort through the knowledge stored in his mind and test new possibilities.
The days passed as the training continued.
Akeno, Kiba, Rias, and Koneko improved their teamwork dramatically. Their coordination reached a level where they could finally pressure Arthur properly, forcing him to react seriously instead of casually overwhelming them.
Still, their own growth couldn't keep up with his.
No matter how much they improved, Arthur's progress was even faster. By the end of the week, they still hadn't managed to defeat him even once.
During that time, Arthur asked Koneko if she wanted to train under him directly. After receiving Rias's permission, she accepted without hesitation, officially becoming something like his disciple. He planned to continue teaching her in the future, as her physical aptitude and discipline made her especially suited for his martial arts.
By the sixth day, Rias's personal training finally began to show undeniable results.
She managed to condense nearly twice the amount of power of destruction into a single sphere, maintaining stability far longer than before.
Today was the last training session of the camp.
Since it was late, only moonlight illuminated the training grounds, bathing everything in a faint silver glow.
"Since it's our last chance," Arthur said while they were taking a short break, "why not try something different?"
Rias turned toward him, the moonlight reflecting off her crimson hair.
"What do you have in mind?"
After living under the same roof for an entire week and witnessing Arthur's strength and judgment firsthand, Rias had come to trust him deeply.
"How about using all your power at once?" Arthur suggested. "You hit another wall yesterday, didn't you? If you keep stopping there, it might take years to move forward. But if you commit everything… you might break through."
Rias fell silent, thinking carefully.
He wasn't wrong. The previous day, she had clearly felt herself collide with a limit she couldn't surpass.
"…Will you be able to contain it if it gets out of control?" she asked quietly.
Arthur smiled with complete confidence.
"Of course I can."
Rias didn't know whether to feel reassured or irritated by how easily he said that. In the end, she chose to trust him.
"Okay," she said firmly. "Let's do it."
She closed her eyes and focused completely on her power of destruction.
A deep, dark red aura erupted from her body, thick and oppressive, while Arthur simultaneously expanded his Anti-Magic, enveloping the surrounding space with his own dark energy.
Rias pushed harder.
Her power surged violently, growing denser and heavier by the second. Whenever it threatened to spiral out of control, Arthur's Anti-Magic devoured the excess instantly, preventing any damage.
She didn't stop.
Trusting Arthur completely, Rias focused solely on releasing more power. Soon, her aura became so dense that it fully concealed her form.
Arthur activated his Six Eyes at full capacity, piercing through the layers of energy to monitor her condition.
Second by second, the pressure increased.
The power of destruction began pushing back against his barrier, trying to overwhelm it. Arthur responded by reinforcing his Anti-Magic, dedicating nearly half of his Dragon Heart's output to containment.
Minutes passed.
Then an hour.
Then two.
Arthur remained perfectly stable, but one thing puzzled him deeply. Rias's reserves of demonic power still hadn't run dry.
Then, suddenly, the pressure shifted.
The power of destruction surged one final time, far stronger than before, before abruptly stabilizing.
The dark red aura vanished.
Rias stood there once again.
The moment she opened her eyes, realization struck her all at once. Emotion flooded her chest, and without thinking, she rushed forward and wrapped her arms tightly around Arthur.
"It worked!!!" she exclaimed, her voice trembling. "Somehow my demonic power reserves have skyrocketed! I can feel it. I'm at least five or six times stronger than before!!!"
Rias was overwhelmed with happiness. For the first time in her life, she felt that all her effort, frustration, and fear had finally paid off.
"It worked. It really worked…"
Her voice trembled as she laughed softly, still clinging to Arthur as if letting go might make everything disappear.
"I'm glad, Rias. Truly," Arthur said, relief clear in his tone. "But… your clothes…"
She froze.
Confusion flickered across her face before she slowly looked down, realization hitting her all at once. Her demonic power had completely disintegrated everything she had been wearing.
Her cheeks burned, but instead of stepping back, she tightened her grip around him.
"Look at the sky," she said quickly, pressing closer.
"Yes, ma'am," Arthur replied without hesitation.
He kept his eyes raised, focusing on the moonlit clouds, even though his enhanced senses had already betrayed him. His memory recorded everything with perfect clarity, whether he wanted it to or not.
If he had not possessed absolute control over his body, this situation would have been impossible to endure. Being held like this by a naked girl under the quiet night sky was a brutal test for someone who had lived most of his life alone.
"Turn around," Rias said softly.
He obeyed.
The night air brushed against his back, and then warmth followed. Rias pressed herself against him, her arms slipping around his waist. Her skin was warm, her heartbeat fast, and her breathing uneven.
For a moment, neither of them spoke.
"It's been a while since I asked you," she murmured. "Are you sure you don't want to join my peerage?"
Arthur remained silent. The forest seemed to hold its breath.
Finally, he answered.
"I'm going to refuse again. I already told you. I'm not interested in being someone else's servant."
Rias flinched.
"I see… I'm sorry for asking again."
She tried to pull away, but his hands closed firmly around her wrists, stopping her.
"Aren't you curious about the reason?"
She hesitated, then nodded.
"Tell me."
Arthur inhaled slowly.
"It's because I don't want to stand below you," he said. "I don't want to be your servant. I want to stand beside you. As your equal."
Her heart skipped violently.
Her face burned as those words sank in. It felt unreal, like a scene pulled straight from the romantic novels she read in secret.
"I… see," she whispered. "That makes me very happy."
She paused, then spoke again.
"Can you turn around?"
Arthur turned to face her.
For a moment, they only looked at each other. Moonlight framed her crimson hair, her eyes shining with emotions she did not try to hide.
Then she stepped forward.
Her hands pressed lightly against his chest, fingers trembling. She leaned in slowly, deliberately, giving him time to stop her.
He did not.
Their lips met.
At first, the kiss was gentle and uncertain, almost fragile. Neither of them moved, as if afraid the moment would shatter if they did. Arthur felt the warmth of her breath, the softness of her lips, the faint hitch in her breathing.
Then Rias leaned in more, deepening the kiss.
It was not desperate, but it was intense. Her lips moved against his with quiet determination, her fingers tightening slightly in his clothes as she poured everything she felt into that contact.
Arthur's thoughts vanished. His body responded before his mind could catch up, his lips moving with hers, matching her rhythm, returning what she offered.
Time seemed to stop.
When they finally parted, their foreheads rested together, breaths mingling, hearts pounding.
"See you tomorrow," Rias said softly.
Before he could respond, she turned and ran toward her room, her steps light but hurried, leaving Arthur standing alone in the training yard.
He stayed there for a long time, staring at the empty space she had left behind.
"Ara ara~ I think everything went well…"
From behind a distant pillar, a familiar shadow watched quietly before retreating into the darkness, a knowing smile lingering as she slipped away to her own room.