Another Stupid Isekai - Chapter 29

Once she transmigrated over, Li Haitang, an elite female doctor from the big city, is demoted to a pitiful little cabbage whose parents have both died. She is surrounded by extreme jackals, wolves, tigers and panthers family and relatives. What? She is sold to a half-dead body that is going to be buried in the ground. Has she been sold to an old man with a heavy taste? The only way to escape from the arranged marriage is to pack a bundle wrapped in a cloth! Who would have thought that on the way to the wedding, she meets a wild man who is feared by everyone in the village? The wild man has three treasures, he is hardworking, spoils his wife and has good stamina! His pectoral muscles, abs and mermaid’s line are all there.

- Description from Novelupdates

The Gura Gura no Mi is known as the strongest fruit in the world of one piece.

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.

I finally managed to kill the demon lord.