MTL - Shoujo Grand Summoning - ~ 026 can give birth to such a daughter, it is also the best

This is a story that follows the courtship between a stone from Hell and a god from Heaven that begins in the underworld and spans for three lifetimes in the mortal realm.

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

Jeong Jiheon was once a promising swimmer, but retired early due to an injury and is now working diligently at a sports agency. Currently, the greatest interest in the sports market is none other than Kwon Jaekyoung, and numerous agencies are fighting fiercely behind the scenes to scout him.In the meantime, Jiheon is ordered by his boss to somehow arrange a meeting with Jaekyoung, and he miraculously succeeds thanks to their insignificant and brief relationship of going to the same swimming center 10 years ago.However, when they agree to meet for the first time in a long while, Kwon Jaekyoung is not interested in the terms of the contract. He just suddenly asks about Jiheon’s traits….

The only Paladin of the forgotten god, Nameless Chaos, and also the only Pope, Priest, and Worshipper.