Isekai Saikou no Kizoku, Harem wo Fuyasu Hodo Tsuyoku Naru

Yuuto’s life changes forever when he is suddenly reincarnated into a fantasy world resembling a smartphone game, born as the third son of a noble family. In this new reality, individuals possess unique abilities known as skills, and Yuuto is granted an exceptionally rare one called "Noblesse Oblige." Upon reaching adulthood, he discovers the true nature of his power during a ceremonial union with a woman: his skill activates, allowing him to perfectly copy any ability she possesses. Driven by this extraordinary gift, Yuuto begins seeking out women who hold powerful skills, embracing them one after another to absorb their strengths. As his arsenal of copied abilities grows, he steadily ascends toward becoming the most formidable force in the world. Along the way, the women he takes into his life genuinely fall in love with him, allowing him to build a devoted harem. Yet the potential of "Noblesse Oblige" extends far beyond mere replication. It is eventually revealed that his skill can also awaken dormant abilities within others and evolve existing powers to unprecedented heights. With every new partner and every stolen or enhanced skill, his advantages compound endlessly. Claiming every woman and ability he desires, Yuuto embarks on an unstoppable journey as the ultimate overpowered noble.