I loved how they started the manga making the readers stay till the very end and how they used multiverse universe concept here. Also giving us a moral that we can not change the past but what we can do is not repeat the same mistakes over and over again. Having guilt is good as it let's you know you did something wrong and keeping guilt isn't. You must erase all your regrets..
The story just literally teaches us the fact that life goes on.. it doesnt stop for anyone. You shouldn't stick onto one thing for the rest of your life. Move on and live your life the other way.. it's not possible that only one shoe fits you right? If it fits right doesn't also mean that there isn't any other shoe that will fit you too. How you know which one is more comfortable if you don't try?
I swear what in fictional world is that... he came ALL THIS WAY?