Valhalla Saga - Chapter 162

Lyle Walt is a young noble boy and heir looking forward to the day he can inherit his family’s territory. Except around when he was 10 year old, his parents started neglecting him more and more in favour of his little sister, Celes.
On his fifteenth birthday, he is challenged to a duel by his sister to see who will inherit the household and horribly loses, being cast out of his family. Afterwards, he gets treated by the family groundskeepers and receives the family heirloom Gem from him that Lyle’s grandfather had entrusted to him. From there, he begins an aimless journey with his childhood friend and former fiancée, Novem, and the Gem-turned-Jewel that houses the memories, personalities, and Skills of seven of his ancestors.

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

After transmigrating into a weak noble body, Marvin discovered that he was familiar with the world, this was the game he played in his previous life and… Damn! He only had six months before the Great Calamity!

After an unforeseen circumstance, Kayn is abruptly transported back in time, accompanied by someone he once considered his most significant foe. As he delves deeper into the past, Kayn discovers the truth behind the events that led to his betrayal by both his guild and allies, as well as the agonizing reality of being abandoned by those he was sworn to protect. Fueled by a deep desire for retribution, Kayn vows to take matters into his own hands and right the wrongs of the past, proclaiming his intent to become a Kingmaker and shape the future according to his own vision.