Global Killing: Awakening SSS-level Talent at the Beginning - Chapter 2:

Vahn decides to spend a bit of time with Sarina in the Actualized World of Dragon Ball.

A man was transported to Ancient China and eventually became a servant of a declining household without a male heir. He utilized his wits and modern knowledge to help the household and eventually become trapped in the sea of political turmoils of the period.

- Description from Novelupdates

Rin was a nobody—just a gamer with a love for manga—until death dragged him into another world.Reborn as Auren, the third prince of the cruel and war-hungry King Aurelus of Austerra, he enters a realm ruled by magic and divine systems. Every person is born with a Divine Frame—a gift that defines their class, power, and fate.Everyone… except him.Frameless. Powerless. Disposable. Auren is cast aside as a mistake that shouldn't exist. But hidden beneath that flaw is a terrifying truth: no Frame means no limits. With nothing holding him back, he begins mastering all paths—mage, warrior, healer, assassin—enhancing them with Earth’s forgotten science.In a world that thrives on order, Auren is chaos. And from that chaos, a legend is born.

A wicked mother one day brought home a girl. The child was the hidden legitimate daughter of the duke, the heroine of [The Duke’s House Has Three Sons and One Daughter] Loretta. I was Melody, the villainous girl who tormented her and was condemned along with my mother. Not wanting to die like that, I decided to start treating her well now. I personally fed Loretta, put her to bed, and played with her. And then her reaction was…? “I want Melody to marry me!” Caught off guard by her endless affection, I too ended up entering the duke’s family, “I’ll stick right by Miss Melody’s side.” And there, it seems I’ve met a young lord who’s an even bigger ‘Melody fool’? All I did was be kind to survive, but why am I being loved…?!