MTL - Demon Slayer Starts From the Proficiency Panel - Chapter 15 [015] out of the mountain

Once upon a time, a boy was referred to as a “War Hero.”

In another world called Aletia, the boy who had saved the Lost Kingdom, conquered their neighbouring countries, and led to the rise of a grand empire decided to throw everything away, returning to the modern era at the cost of his memories.

As three years passed, the boy who was happily enjoying his daily life was once again called back to the other world.

However, what awaited him was the Aletia of 1000 years in the future.

As his past glories became a “myth,” the legend of the youth referred to as the, “Twin Black Hero King,” begins.

[Power System has beautiful Waifus as his spirits.]

[Read for the great plot and a perfect HAREM. There will be SMUT chapters only when required. The protagonist isn't Naive and treats his woman with care.]

[Read only if you want a great plot, sweet romance, a perfect harem, and good smut without any forced development.]

[Story would make sense as you progress I have avoided info dump and explained in a natural way to answer each question through the characters.]

*Ding!*

[Dual Cultivation System installed]

…

Yue Yan Gets kidnapped by the goddess on his sweet night with his girlfriend. She asks him to help her on a mission against the XieLong temple but he turns her down.

Later, some mysteries reveal their past and Yue Yan agrees to help her in order to meet his Bing'er again who has also been sent to the new world.

When he transmigrates into the body of Meng Long, he finds out he has a special Physique, the Supreme Yang body that stops his growth in Cultivation unless he Dual-Cultivates with a woman.

Yue Yan's new family had mistreated his predecessor Meng Long so he decides to leave the clan to embark on a new path with his beautiful concubine Xue Rou.

Join Yue Yan AKA Meng Long, in his Journey to reach the pinnacle of the world.

A Federation Colonel with abnormal thoughts was locked in a dark room and met a little looney.

“Your whole body emits a scent that I dread (covet) and fear (desire).”

A frigid Colonel X little looney roommate: A sweet story of interstellar travel

- Description from Novelupdates

Wei Yuewu is the unloved daughter of the powerful Marquis Hua Yang.

On her way back to the capital city to marry her fiancé, she becomes the target of a ruthless assassination led by her fiancé, Marquis Jing Yuan.

With the help of the Prince of Yan State, she narrowly escapes from one disaster after another and returns to the capital.

Determined to avenge her enemies and unravel the mystery surrounding her engagement with Marquis Jing Yuan as well as the death of her mother, Wei Yuewu makes a deal with the Prince of Yan State.

However, just as she has triumphed over all her enemies and is about to reach the acme of her life, she deliberately destroys her own future and becomes an exile of her own…