Great concept. Great storyline. Some reckless details but very few. However, the ending is very lame and feels like cheating.

Just before the ending, the ML can suddenly touch anything in the past just to clear the game—this is cheating #1. Then, his son can bring anything from the past at the age of 5, when he doesn't even understand the concept of the past. He doesn't know what a 'year' is, so we can't even talk about how he understands '18 years ago', but the FL can persuade him to bring the ML back from 18 years ago...? And they don't make it realized about his method for bringing things back from the past either, so it feels more like magic than a superpower. They make it too convenient without rationality. So that's cheating #2.

P.S. I usually give music scores an average of 5 because I don't consider myself an expert in that field. If the music isn’t exceptionally good or bad, I might not notice it, so I try to be fair. But this series has put the wrong music in the wrong places and at the wrong times quite often. For example, when the ML goes back to meet the FL in the past for the first time. It happens under a serious atmosphere, but a light, funny music suddenly starts at that point -_- The music sounds out of place and doesn’t match the mood of the scenes. It's noticeably off.