in sapphire and beryl (Xiao lu He Xiao lan) there's one mini plot where one of them remember things backwards, so he knows everything about his future but nothing about his past, so he keeps a diary, which I think would be much nicer bc then you would read your own point of view on what happened in your days
also just an excuse for me to recommend sapphire and beryl, just search for it I guess you can watch it on YouTube since it's so not known at all anime lol
Also in case you haven't watched the film that's mentioned in the manhwa, it's called A moment to remember (in English) and it's SO GOOD.
Reminds me of the movie fifty first date. Yesung should keep a recorded video of themselves and maybe a brief yet concise explanation of how they got together. so he doesn't have to repeat himself over and over whenever sihoo lose his memory. Oh, well... It truly was cute.