rival's absence

What do you think is the reason for every rival to not be at school before their week ?

We know Megami have some "family business",

Mida is obvious but for the others it's hard.

Maybe Kizana left to act in a play,

Asu went to a competition,

Mija could have call in sick,

Amai may work at some place that need her to be here 1week/2weeks,

Hanako may be super intelligent and just went up a grade,

Osoro might have excluded for some weeks because of her deliquents activities,

And Oka could see some kind of doctor who told her to not go to school for some time due to her bullying.

The order is kind of messy but I tried to order them by obviousness.