A Mastermind? No, I'm just the Live-In Son-in-Law - Chapter 12: The Engagement Ceremony

A continuation from where High School DxD Volume 25 left off.

The protagonist of a war fantasy novel, Theo, competes with his rival and antagonist, Luke, for the position of Supreme Commander. Having been reincarnated into Luke’s role, he struggles to fulfill his duties as the villain. “It seems like principles as a soldier, the duties I should uphold, don’t matter to you at all.” Even if misunderstood by Theo, Luke silently remained faithful to his role as the antagonist. After completing all his duties, Luke successfully gave Theo his happy ending, cast aside his military uniform, and retired from the army. Now, Luke planned to create his own future story without interference from anyone. That was the plan, at least… “Why go this far? I’m no longer a soldier, and if you really think about it, we were never on good terms anyway.” To make matters worse, not only had he unexpectedly reunited with Theo, but now, Theo was persistently and seriously pressing him in a way he hadn’t imagined. “I want to know you better.” It was a completely incomprehensible statement, and it wasn’t even an appropriate answer to the question. The protagonist came to the antagonist and suddenly asked for help, simply because they wanted to know him better?

In a world governed by the mysterious power of dimensional gates, young Dabi, once frail but gifted with a photographic memory, discovers his life-altering ability: a leveling system that grants him new skills and magic as he rises through the ranks. After his family perished in a gate-related tragedy, Dabi swears to protect his siblings and unravel the mysteries within these deadly portals. Alongside his loyal spirit pets and rare allies, Dabi faces ancient threats and powerful enemies tied to his parents’ tragic past. As he rises in power, Dabi’s quest draws the attention of noble families, dangerous royals, and sinister forces seeking control over dimensions and the future of humanity itself. Secrets, betrayals, and a growing vendetta lead him deeper into a battle that threatens the fabric of existence. With the fate of his world hanging in the balance, Dabi must outwit and outfight forces beyond imagination all while confronting the truths hidden within the gates of the lost dimension.

18 years have passed since I was born as Allen, the eldest son of an earl in this world, while still retaining my memories of the present world. This world is peaceful and a stable society. The only extraordinary thing is that I was reincarnated into a world that is lenient on the existence of concubines. I selected a silver-haired maid as a sex slave and second wife candidate from among 10 candidates after a strict fellatio practical exam. I then lived an erotic life at home and at school as an attendant, but my reincarnated life is so fulfilling that I'm worried it will explode, as my busty childhood friend, a noble girl who was unsuccessful, ran for the third wife candidate, and my stepmother, who was my virgin partner, was sold off.