@zz2000 there was a chapter where Lippe and Hal had a conversation about politics in a café. That was the only time we’re given hints of possible perpetrators.
To refresh our memory: the Rustichel’s (Lippe’s family) are a count house, who are in charge of an imperial knight division.
Lippe asked Hal what family has enough power to bring a family like her’s to ruin. Hal said despite not having a lot of political power, being in charge of an imperial knight division makes the Rustichel’s more powerful than any other Count houses. The only houses who can put the Rustichel’s to ruin would be either Ducal houses (Castillo or Samona) or the imperial family. But for it to be so secretive, at least 2 of them have to be working together.
We know Asterias is from house Castillo (the white haired, blue-eyed boy) and Hildert is from house Samona. We haven’t been introduced to anyone from the imperial family yet.