Rimuru The Void God In The Future Past

After Feldway send Rimuru to the end of time and space Rimuru decide to find a way to go back when he's wake up but Ciel tell him that his timeline had already destroyed so he cannot go back

after hearing that Rimuru start to feel a lot of emotion inside him sadness regret and pain all the emotions you can think of come to him at once and start to make him go insane

Ciel after seeing this decide to seal his memory away and cause him to go to a long sleep, and when Rimuru wake up had no memory of anything about himself only his name start to go on his own journey