Ikebukuro area
From BOOK STORE WIKI
Junkudou japan main store
Huge. this bookstore has most books in Japan. they has a lot of genres and minor books too. you can use chairs. there are English books on top floor. locates in Ikebukuro South East.(take 4 minutes from Ikebukuro Sta.)
Libro
this locates in Ikebukuro East side building. that is why convenient in case rainy day. they have many casual books collection.