"You are Muriel, the Supernatural Being that can become invisible, Yog-Sothoth... right?"
Katerina had obviously heard of Muriel from Marvin, the only Supernatural Race capable of invisibility, living in the cracks between death and reality—the Land of Mists. Were it not for Mr. Butler luring it with 'Bait' imbued with divine essence, Marvin would not have been able to convince it to stay.
Muriel, meeting Katerina for the first time, expressed confusion upon hearing her call out its name. Katerina was very friendly, instructing Bodrilinov to bring out Silver Melon Seeds from Ailan, and with a smile said: "This is a gift for our first meeting; I want to be friends with you."
[Friends...]
"Yes, friends, Father Marvin is also my friend, you must have seen how he treats me just now."