Unlike Sirzechs and Serafall, who held absolute power, Leohart was hamstrung by the Cardinal Council—a group of ancient, decrepit devils who clung to the "old ways." These elders were literal monsters, looking nothing like the human-looking modern devils. They were greedy, cruel, and viewed humans as trash.
They saw Leohart's rising influence as a threat to their power and decided to betray him to the Old Satan Faction. Their price? They wanted to keep their right to oppress and exploit common devils. Every year, thousands of young female devils disappeared in Leohart's territory, victims of the Council's depravity.
Suddenly, Mio received a letter from the Underworld. It was from her uncle, Ramsas, "inviting" the daughter of the former Demon King to return to the Demon King City as a "Princess."
Ethan saw through it immediately. The elders weren't just after Leohart; they wanted Mio's power. They planned to kill or capture her during the chaos of the coup, blame it on the Old Satan Faction, and wash their hands of it.
"They just won't give up, will they?" Shella, the loli-looking elder devil, scowled. "I always suspected the Council was behind Wilbert's death."
"If the Old Satan Faction is involved," Akeno suggested with a smile, "we could just tell Sirzechs and Serafall. Three Demon Kings against one coup..."
"No," Rias interrupted. "That would expose Katerea. Plus, a cornered beast fights hardest. It would cause a civil war that would slaughter the common devils. We need to handle this quietly."
Ethan grinned. "Mio, write back. Tell them you're coming, but you're bringing 'friends' for a visit. If they say no, you don't go."
The Council wanted Mio alone, but they couldn't refuse a "Princess" bringing a friend or two for a tour. After some back-and-forth, Ethan, Rias, and the girls finalized their plan.