**Major spoilers ahead*\*
Recently I was scrolling on tiktok and came across a comment criticizing Ushio's death. They were essentially saying ushio's death comes out of no where, even taking into account her being tied to the town.
This got me thinking, I wanted to find out if this would actually be a fair critique for the work as a whole. At first I was finding myself stumped. I couldn't find a good answer for this. But then while i was just thinking about it, I remembered the title to one of the songs used in the anime.
"A New Life Reborn" is one of the most poignant tracks used in Clannad's anime adaptation. I want to specifically note the first time its used: that being Nagisa's death/Ushio's birth. This gave me the idea that as Nagisa died, she passed on this tie to the town's nature's state, and when Ushio was born, she inherited the town's current state at the time she was born.
To try simplifying this, I used the metaphor of a gas tank.
At the time Nagisa was saved by Akio's wish, the town was quite lush with greenery. She was in turn tied to the land in the town at that state. As the town underwent change, her 'tank' of life depleted. Upon giving birth the Ushio, she could no longer hold on any longer and ultimately passes away.
Upon being born, Ushio got a new 'tank' of life, but this one was tied to the state of the town's greenery at that exact time, making her tank much smaller/weaker. And in the end, after 5 years had passed, upon getting a normal fall/winter time fever, her lack of 'life' in the tank couldn't sustain her any longer and she ends up passing away.
This would explain how and why it seemed her life was more fragile than Nagisa's, passing away much earlier and at a much easier expense, that being a fever over child birth.
Not only does this theory explain Nagisa/Ushio, I think it also explains how Fuko was able to manifest as a spirit and why people began forgetting her.
To put it simply, I believe there are different types of bonds with the town. Nagisa and ushio were tied through the land. Within the story, the town is pretty much a living being that can respond to deep emotions. So I think Fuko's strong wish to help her sister out/get people to go to her wedding was what allowed her to manifest as a spirit.
But just as Nagisa and Ushio, Fuko also has a 'tank' tied to her spiritual form. Unlike them, however, it is fueled by people acknowledging her existence/remembering her. However, as her condition in the hospital worsens/becomes more known by the people throughout the school, her ability to be seen by them begins depleting, just as if her 'life' tank is running out.
By the time almost everyone forgets about Fuko, her 'life' tank is so low that even those closest to her begin forgetting about her, including Tomoya and Nagisa. But in the end, the efforts of what seemed to be meaningless starfish carvings ended up flashing the reminder of the wedding in everyone's minds. As they all show up, acknowledging Fuko's starfish, this gives Fuko the final boost to be able to manifest once again and congratulate her sister. Upon completing her goal of helping her sister, her manifestation's purpose is served and she pretty much disappears for the time being, at least.
I believe the illusionary world, more so taking into the account of the town being a living being, explains almost all of Clannad's supernatural elements. Everyone who has had an experience with the town as a living being seems to be deeply connected at some level.
Katsuki Shiima being able to show Tomoya his memories is likely because of his connection to the light orbs/town. He wished deeply to be able to grant Misae a wish, and was able to manifest another version of himself through his cat (Which could also be running on some sort of 'life' tank of sorts) to set out to complete it.
This would also explain why Nagisa and Tomoya seem intrigued by eachother in the very first episode aswell. Because they're linked at a deeper level through the town/illusionary world.
Definitely interested in hearing other peoples thoughts on this theory!!!