Tensei Shitara Slime Datta Ken (WN) - Chapter 44: And thus we finished the city

After being given up on by his family because his dantian was destroyed, Soh Woonhwi was kidnapped by the Blood Cult and lived as a third-rate spy.

One day, he died while being used to find a legendary sword immortal’s secret records. However, he returned to the day he was kidnapped ten years ago and obtained a mysterious ability that allowed him to hear the voice of swords.

Seven years ago, Shen Qianshu is impregnated with Ye Ling’s child in an accident.
Seven years later, the little boy becomes famous and is thought of as the nation’s son.

When he suddenly sees Ye Ling appear, he greets, “Hello, Daddy?”
Ye Ling watches as the little prince roars, “Where’s my princess?”
Just as Shen Qianshu is preparing to run with her son, she gets pushed down by Ye Ling.

“You can leave if you want, but leave me a princess first. Let’s have another baby!”

- Description from Novelupdates

This is a world where humans, demons and mysterious beasts coexist. Humans cultivate mysterious qi. Demons cultivate corporeal bodies. Mysterious beasts cultivate soul perception. A legend says that in the middle of an endless rainforest, there are extremely powerful existences; they are called demon kings. Some demon kings have a tyrannical corporeal body, some are experts in illusions. Some demon kings are proficient in magic, some can even move mountains. Some demon kings are able to sense things thousands of miles away. These demon kings rarely appear in the human world. Even if they emerge in the human world, they would reincarnate in human form; assimilating with mankind while seeking to breakthrough realms…….

After a god screws up and accidentally takes high schooler Shou’s life, he offers him reincarnation with a gift to make up for it. Shou asks to retain all his old memories for the new life. Shou is reborn as Will, a noble’s son in a world where magic use is common and involves knowledge of kanji characters. With all his memories, he’s a brilliant toddler, and when he experiments with magic, he finds that he has an amazing talent for it! What’s more, though he was smart but unloved in his old life, in his new life he has a mother and a father who both love him deeply. His future as Will is looking very bright and cool!