A Dragon Idol's Reincarnation Tale - Side Story 55: Da Capo—Repeat From the Beginning.

Karl Wagner is a disgruntled middle-aged instructor at the Bundeswehr Command and Staff College. He finds himself concerned about the direction which the German nation is headed in—just as he is killed by a terrorist attack. Only to awaken and find himself reborn as an infant, Bruno von Zehntner, the youngest son of a noble family renowned for its part in the German war industry a few years after the founding of the German Empire. Bruno, as he is now known, desires to rewrite history and ensure the German Empire emerges victorious in the coming century. And in doing so, finds himself entrenched in a world filled with Blood and Iron!

An ineffable rebirth, taking advantage of a mystical magic cube that was produced from rebirthing to pass through various worlds(anime, novel, movie, games, etc), collecting whatever I want to obtain!

- Description from MTLNovel

Jian Rushi, born in a rich family, was a college girl. Due to some economic reasons, her family went broke. Her father committed suicide under great pressure, while her mother ran away with someone else, leaving her alone in this world. As she tried to find some comfort from her boyfriend, she found that her boyfriend cheated on her. Feeling devastated, Jian Rushi thought of ending her life. But she wanted to do a crazy thing before that. Suddenly she remembered she was still virgin. So she decided to sleep with a man before she died. She went to a pub one day and saw a pretty man drinking there alone. She mistook him as a money boy and took him home. After they slept, she had no money to pay him. As the compensation, Jian Rushi became the mistress of that man, who turned out to be a golden bachelor. And a series of embarrassing things happened…

- Description from Novelupdates

He was very happy to be reborn, but why was he sixteen again, he can’t bear to look back at that time.

Why does he return to being sixteen years old, yet still meet Doomsday?

It’s alright to encounter the end of the world, so why did he have to fall in love with someone?

Even if he falls in love with another person, why did it have to be a man?

Falling in love with a man is also alright, so why did it need to be a secret one-sided love?

Even a secret and unrequited love is alright, so why is that man his….

- Description from Novelupdates