Since some light has been shed on Ayari's father, I wonder if there will be something about Sachi's mother at some point. If I remember she was only ever mentioned once by Eri in an early chapter.
I hate those kinds of pressure cookers: They work badly, lack some basic functionalities, and go bad easily or the parts get jammed. They are advertised as an improvement over the other types of pressure cookers but they are way worse.