MTL - Mermaid Effect - Chapter 27

Diablo Volfir, a mighty magician, was sealed for aeons due to the schemes of the 12 Gods, but 66666 years have passed since then, and he descends to earth once again!

Power and desire, money and strength, conscience and responsibility, the road ahead is at a loss, as a time traveler, Simon, where will he go, this is a leading mainstream novel with a relaxed daily life and a slow pace

- Description from novelbuddy

They had been together since high school. Together, they faced the cold faces of their parents and the satirical or disdainful eyes of others, started a business and experienced all kinds of ups and downs. When their company was on the right track, Zhishu He was asked to give up his career to stay at home, while Wenxu Jiang gradually changed and began to indulge in merry-making. However, Zhishu chose to forgive him. Zhishu got an incurable disease, while Wenxu Jiang was still indifferent. Zhishu still chose to forgive him. Love had become a kind of habit, which was equal to an incurable disease.

In a peaceful sunny day, Zhishu quietly left Wenxu Jiang and the house in which they had lived for a long time without an advance notice.

Soon he was gone. A man with pure spirit and deep love for Wenxu Jiang disappeared from this world forever…

Sometimes love cannot stand the test of time. Someone will not know how to cherish the love until he loses it…

- Description from Novelupdates

With the Goddess’ blessing, he became a 『Divine Knight』 and founded an Empire.
As time passed, he grows older, and by the time the heavens called for him to come, the Goddess showed before him, asking for his last wish.

He wished to be reincarnated in the future.
He dedicated all his life for his people, he had no time to master his own arts.
This time, he wishes to live for himself, forging his body to the utmost limit.

The Goddess complied with his wish.
In the far future, the King shall reincarnate as the 『daughter』 of a renowned Knight family.
And, under some circumstances, she is labeled as a failure of a Knight, however——

「How convenient. I can stand on the foremost line without needing any rank. No better training than actual combat!」

Thus, the legend of the world’s strongest, most beautiful Knight Disciple (♀) has begun—