The Only Player in 'Child of Stardust' - Chapter 99 - 79 The Fish Dies and the Net Splits

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.

- Description from Novelupdates

I opened my eyes to find myself in another world. For some odd reason, I ended up as a sword. Before my eyes laid a plain full of magic beasts, and so, I launched my body and flew in search of a partner, a wielder (females only).

“Gu Hangshen! Your sister stole my man, and you helped her do it! Your whole family is rotten!”“Whatever my sister owes you, I'll compensate you.”“And what will you compensate me with?”“Me.”“...”Later, he not only gave himself up as compensation, but he also came with a clingy little bundle of joy...

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.