Ι have read the first book and I want to read the others as well in english but I am from Greece. I speak fluently english but I am not sure I can manage it... Can anyone non english tell me if it is an easy book to read?

I felt the same way that 당신 do, and at first I wasn't sure if I could read the other books. Yet, the other 책 are just as the first one 의해 language. There might be some confusing parts, but mostly, the 책 are just great and simple. Hope you'll enjoy 읽기 them! :)