Tensei Shitara Slime x Fate Grand Order Crossover

This fanfiction was inspired by author Seike (please check him out) 10 years after the defeat of Yuuki... Rimuru was now the most powerful being in the entire world. However, one day, he realises that he can no longer sense his parallel self on Earth. He returns to find humanity destroyed. After meeting the User of the Second True Magic, he becomes a servant, alongside some friends