I think he also came back in time and the heart part would make sense
It’s heavily implied since he’s being very hostile and wary of any threats that popped up in the previous life, like with the kid who pretended to lose his voice.
And in a previous chapter she gave her heart to him since he was either in the brink of death or dead.
I almost forgot she did that thanks for the reminder
I think the reason he remembers is because of her heart, since it was stated a Saintess removed her heart and reversed time once long ago.
And since she’d remember the past, him having a piece of her triggered his memories.
Why do i think that eddie also come back in time and he the one who has belze heart? It possible right
ヾ(❀╹◡╹)ﾉ~