God of Money - Chapter 36:

I’ve become the ultimate crafting all-master character in a game world, excelling at everything except combat.And now, I am the only one who can save this Northern Grand Duchy.

“The lifespan of a butterfly is between three days and a month, and most butterflies only live for a week.”
“Like them, I have only a few months to live, maybe less.”

–

The first time Hu Die met Jing Yu, he thought she was a world-weary girl who committed suicide.
The second time they met, he told Hu Die indifferently: “If you jump down again today, I’m not saving you again.”
Later, she told him: “Jing Yu, don’t feel sorry for me.”

Later, Jing Yu returned to the arena and won the glory that belonged to him.
Under the flashing lights, he suddenly remembered the girl’s voice, and said a nonsensical remark in front of thousands of people.

——”I’m not sad, I just think that at such a moment, it would be better if you’re here.”

“He is a whale swimming in the ocean. One day, a butterfly inadvertently broke into his frequency. That was the most beautiful moment in his life.”

- Description from Novelupdates

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.