[DeepL Translation - needs review] Volume 1 Introduction: One day, four siblings enter a large wardrobe that leads them to another world full of snow. In this Narnia, the children fight alongside the Lion of Justice against the Wicked Witch's army.
(Translator: DeepL)
I'm not sure how should I rate this book, the translation by 瀬田貞二 from 1966 might be a bit old. The version I've read was mostly hiragana, it's a children story so it's not hard for natives, but there's a lot of long descriptions of nature, nouns like tree and plant names, lots of onomatopea etc. I think it should be around lv 25~? but it probably would be easier to read with more kanji. The sentences are pretty long but easy to understand (except of heavy keigo and the "royal"? way of speaking