The second requirement for successful Dual Cultivation was the partner's inherent potential.
If a woman's limit was naturally A-rank, no amount of sexual training would push her to S-rank. This was the case for many of the girls Ethan had encountered, like the Takamine mother and daughters, Rena Hamasaki's group, or Sakura Miyajima. It wasn't that Ethan was unwilling to help, but rather that their potential was finite; they simply couldn't keep pace with his explosive growth.
Most of them were currently stuck at the threshold of the A-rank life-essence transition. For some, like Reina Kurashiki, the limit was even more obvious. Since hitting C+, her progress had ground to a halt. Without some world-shaking miracle, she would likely never advance further.
Still, without Ethan, women like Reina would never have even glimpsed the supernatural world, let alone stepped onto the path of cultivation.
Ethan had once worried about his own limits, but now that he had reached SSS-rank, those fears had vanished. He felt no bottleneck, no invisible ceiling. As long as he remained diligent in his sexual "labors," he would eventually accumulate enough power to challenge the Satan-class (Great Satan) rank.
However, there was a new drawback. Since reaching SSS-rank, sleeping with girls of a lower level provided much less "experience" for him. Unless he successfully conquered a woman of his own rank or higher, his progress would be a slow, steady grind of accumulation.
Back in the clubroom, Rias suppressed her stray thoughts and pulled a shivering Gasper out of his cardboard box. The blonde boy was still trembling, muttering about how "scary" the outside world was. Rias's natural aura of authority and safety eventually calmed him down. She had an innate charisma that made people want to follow her.
"Little Gasper," Rias said softly. "Would you be willing to become my servant?"
"S-servant?"
"Yes. Through the Evil Pieces..." Rias held up a chess piece shimmering with a strange light. She gave him a brief rundown of the reincarnation process.
Gasper didn't fully understand the mechanics, but he was drawn to the piece in Rias's hand. He nodded instinctively. "Y-yes. I'm willing-pya." His voice shook, but his resolve was surprisingly firm.
Rias smiled. Through her senses, she knew that of her remaining pieces, only the mutated Bishop could handle Gasper's massive potential. She wasted no time and began the ritual. A crimson magic circle bearing the Gremory crest manifested beneath Gasper's feet.
Reincarnation was usually a simple fusion of the tool and the soul. But just as the mutated Bishop began to sink into Gasper's chest, the blood-red magic circle shattered. The ritual failed.
Rias stared at the Bishop piece as it returned to her hand, her brow furrowed. Her intuition told her this failure was somehow linked to Ethan. But that didn't make sense; she had successfully reincarnated Yuma Amano and the others. Ethan's energy within the pieces hadn't interfered then.
While Rias was confused, Gasper was genuinely devastated. He rarely spoke of it, but he craved companionship. He felt a strange affinity for Rias, and even for Ethan, who had forcibly shattered his shut-in lifestyle. Despite his fear, he looked up to Ethan—he wanted to be that strong, that decisive.
"Rias-senpai..." Gasper whispered. "Can we try again?"
"Yes," Rias nodded. There seemed to be no side effects, so she tried a second time. The result was identical: the fusion stopped cold at the final step.
Rias's blue eyes flickered between Ethan and Gasper. A realization began to dawn on her. "Ethan, Gasper, wait here. I'm going to find Sona."
Ten minutes later, Rias returned with Sona Sitri, Tsubaki Shinra, and the rest of the Occult Research Club.
"Gasper, Sona is going to try using one of her pieces on you. Just cooperate," Rias instructed.
A blue magic circle—this one bearing the crest of the Sitri family—lit up the room. Sona still had several vacancies in her peerage. To ensure the test was accurate, she also used a mutated piece.
Watching the blue mana, Ethan thought about his own power. His mana was also blue, but it was a deeper, more violent shade infused with the Power of Destruction. Originally, his mana had been a pale blue like Sona's, but after absorbing Rias's and Akeno's talents, it had evolved.
Sona finished the ritual and sighed. "It's no use. Same result as Rias." She looked at Ethan with a very peculiar expression. "It seems your theory was correct, Rias."
Ethan scratched his head. "President, Sona... you think this is my fault?"
"We're almost certain," Rias said, crossing her arms. "Most of your abilities revolve around Dual Cultivation—specifically with women. Sona and I both tried to reincarnate you in the past. Even though it failed, the process 'stained' our remaining pieces with your aura and your unique characteristics."
Ethan looked at Yuma and the others. He finally caught on. "You're saying... because the pieces are 'polluted' by me, they can only be used to reincarnate women?"
"Exactly," Rias said. "And there might be a second condition: they might only work for women who have already been 'marked' by your scent. I'm going to test that now with Ravel."