Shio believes everyone’s heart is a jar made of glass. If it isn’t regularly filled with love, or is hit by various stresses, it will crack and break, and when it does, there’s no coming back.
Shio is worried Satou’s jar is dangerously close to shattering, so she tries to do as much as she can. She covers her with a blanket, warms up the curry, and throws her clothes in the wash—where she sees Satou’s bloodstained clothes.
Seeing Satou in such a state reminds Shio of her last days with her mom, who became destitute when she finally left her abusive husband. Shio wanted to do what she could then too, including replace her mother’s “jar” with a new one she sees across the street.
But in doing so, Shio is almost hit by a truck, and her mom’s jar breaks. She takes Shio on a walk in the rain, then stops and leaves her there, saying a simple “goodbye.” Her mom’s jar was broken, and she was simply…done.
When Satou awakens, she pretends like nothing’s wrong, but immediately starts talking about their next home. After all her talk about the castle where they’d live happily ever after, it wounds Shio to hear Satou so gung-ho about abandoning it.
But more than that, Shio is hurt by what Satou isn’t saying, and by all the things she’s hiding. When Satou tells Shio all she needs to do is smile and love her, it reminds her of her mother, who also asked nothing of Shio but to stay put; to stay safe.
Shio won’t have it; not anymore. She doesn’t like Satou’s secrets, or her vision of how she should be to her, which is to act as little more than a human doll. She storms off, and in her anger, tells Satou she hates her. Satou then becomes paralyzed with despair.
The same night Shio’s mother abandoned her, Satou happened to be walking around, and meets Shio, asking her why she isn’t chasing after her mom. Shio tells her it’s because what she felt toward her mother wasn’t love, it was just a desperate hope her mom would keep living, so she could live.
With an attitude well beyond her not numerous years, she decides not being with her mom anymore is for the best. But she also realizes she was too harsh with Satou. She doesn’t hate her; but she hates how Satou shoulders the burden of protecting her.
From now on, Shio wants Satou to tell her everything, and they’ll share the burden and protect each other. In other words, a more balanced relationship where Shio has agency. Satou agrees, and tells Shio all of the horrible things she’s done to keep her safe, including killing someone. Shio accepts it all and fills Satou’s jar…because Satou fills and strengthened hers.