Only Pon is currently still enrolled in high school, if you remember from Chapter 3, we know that Kon dropped out of high school due to "certain circumstances".
heya! translator for foxachu agency here, it was left unambiguous by mari on purpose. she kind of just spit our that her father died our of nowhere and gave us zero context on how he died, my speculation is suicide.
but who knows?
Now that we have Mari's side of things; and, how it ties into her needing the Love Agency's assistance for her relationship with Seki.
I wonder what Seki's character flaw is?