3部の話好きだけどエイルの設定重すぎない...?
「複数の命」は比喩表現で実はエイルにはたくさんの霊が憑いてて毎日除霊してもらってたんだと思うことにする

I love Book 3's story, but isn't Eir's backstory too dark...?

So that's why I took her title, "Countless Lives" as a metaphor and imagine that she's constantly haunted by evil spirits. So every day, she has her mother exorcise spirits from her.