Okay MC going to diffrent world with his ability to learn and break the story line is topnotch! When you get into thing furthur ahead he just kills lame characters that are jackasses even the original mcs... Then it showed me the truth about a certain character fate being stuck in a prison made by her principal and has to live seeing her fake self love a idiot... Yea That anime gave me a few wtf moments and how the Author took care of that Idea that I wished I knew before... He did the right thing... in killing and taking what his by a thin grey line. Why because the plot of the original didn't progress and really the fates and love dor those character don't matter if Author MC goes and cuts them alll before event occur. Only MC know what truly happened and goes into it with his will and actions.
Harem though with your selection makes sence due to the sad fate of each one... I gope your MC dosn't have issue with the Fate series... if so don't kill mc of theirs pls?
