An (IMO) original and beautiful story about a 15/16-year-old sf/f fan dealing w/ British boarding school & physical disability while trying to come to terms w/ the death of her twin sister in a traffic accident, and (somewhat ambiguously) fairies. It is written in the form of a slice-of-life diary, which also includes her comments on hundreds of major sf/f works & in some sense sketched the English-language science fiction scene up to 1979/1980.
p.s. an interesting thing to do while reading this might be to count how many books one has read so far among those Mori mentioned. (: I haven't read most of them & haven't heard of some of them.