I read it a while ago but forgot to bookmark it. It is adapted from a light novel, I think.

All I can remember is the main character got called to another world by a goddess to be a hero, but she already had her hero so she deserted him. By then, another goddess appear and grant him some superpower, then sent him to another world. In that new world, he rescued a pig girl by killing a cerberus. After that, they headed to a cave of her friends. That night he went to kill a dragon, I think.

I remember the plot quite well but can't recall the titles nor characters' name T_T

I believe it's Tsuki ga Michibiku Isekai Douchuu.

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That's it! Thank you very much!