Riklent
I'm sure many didn't like this chapter, revealing your identity as a reincarnated person is almost a taboo and many times they do it wrong, but you did it perfectly, I think a mother would never understand it, that your son is older than you, can you imagine? In the case of the grandfather, it makes all the sense in the world, because not only does he not understand to what extent the MC has his memories or what kind of memories they are, he is also her only living relative and he deposited all the love he had for his daughter in him. The most important thing is that the grandfather will die, so they won't have to live decades with that knowledge and the MC will be able to get rid of his demons, revealing that secret and maybe feel more calm and loved. It has to be bad to live a lifetime with a secret like that, now he could reveal it to someone dear to him without repercussions. So far so good, but don't reveal it to anyone else, other authors have ruined their stories because they confuse the importance of that secret with the WI-FI key.
A lot of moves are inspired by nature or animals. Maybe you should start thinking in that direction. I feel as if sakura blossoms would be a good one to base a move set on. Maybe the scene of the sakura blossoms remind him of his grandfather and his death. Sakura blossoms are definitely an option though, although they have been used extensively before in other shows.