where the soul is reborn over and over again to be with the mom, even for just a few seconds. Such kind of pure, unconditional love tugs at my heartstring. It may feel irrational, stupid even, to love someone who did such a horrible thing to you. But that's the beauty of it all. He just loves her that much, despite everything. The soul chooses to remember their joyful moments together rather than dwelling in hatred. Either that, or the simple mind of that kid is simply incapable of hate, and he surely would have resented her if he had managed to to grow up. It's quite fitting that the soul is reborn as equally innocent things. And just like everything innocent, his subsequent reincarnations are all short-lived, lest the innocence fades away with time.
Naturally many people would hate the mom and condemn her actions, talking about what she could have done differently. I can see where that comes from, but I feel it's missing the point. This one-shot doesn't invite us to judge the mom or justify her unjustifiable deed, because no amount of condemnation or sympathy can undo what she did. There is no moral lesson, but simply a story of two intertwined souls, one who loves unconditionally and one squanders the love given to her.
There might be a different interpretation of this one-shot. If you cross out all the paradise segments (and with it the supernatural element), this could easily be a different story, viewed through the mind of a broken person. After all, people project their thought and feeling on their environment. From the woman's perspective, she sees her son and hears his voice in any soothing existence around her, whether it's the stray cat she hugs, the wild flower she takes care of, or the raindrops falling on her shoulder. Anything that can potentially gives her some fleeting moments of peace reminds her of the child she used to cherish, the same one she deprived of life. The sense of loss is even more palpable when those comforting little things, being ephemeral, just fades out of existence the next time she looks. It's the embodiment of her late child who is both constantly in her mind and forever out of her grasp.