Isekai is Japanese for another world, MC is short for main character, RAM and REM are characters in an anime called Re:Zero, an anime where the main character gets isekaied and his amazing superpower is that every time that he dies he resets back to a save point.

However, he does not control the save point so he can lose weeks of progress if he fails to advance fast enough, and he dies often and gruesomely most times.