Since I'm in the mood for everything dreams, ghosts and all that, brought along the palm-sized novel for easy reading everywhere. Written by Riku Onda, I'd say the title roughly translates into 'The Different Strange Dreams'.
「夢違」著恩田睦 。ゆめちがい。 Amazon summarizes it as 「何かが教室に侵入してきた」。学校で頻発する、集団白昼夢。夢が記録されデータ化される時代、「夢判断」を手がける浩章のもとに、夢の解析依頼が入る。悪夢は現実化するのか？ 戦慄と驚愕の幻視サスペンス。
The book is prefaced with the same quote from WB Yeats' 1914 book of poems titled 'Responsibilities', in which its epigraph reads "In dreams begin responsibilities".
The book's first chapter is titled 「一章：幽霊」, indicating spirits and ghosts. It sets the scene for us to immediately be acquainted with the ghost of 古藤結衣子 (Yuiko Koto) in the library. We learn about Yuiko's life and some of the disasters (fires, collapse of bridges, collective dreams of three-legged crows, 80 missing school children and such) she predicts. Because of how time is portrayed, i.e. there seem to be a few time jumps when she meets 野田浩章 (Hiroaki Noda) in a psychiatric analysis of a dream. Soon we start wondering how old Yuiko is when we assume she is in elementary school, then we realize she could be in her mid thirties or forties. If you thought her dead 12 years ago in a fire, you'll wonder if she might be alive. 結衣子が生きている場合 Then you wonder if you had been in her dream instead.
There's the introduction of a sleep machine because of the idea of 夢札という技術, where you could go into a dream at will, and record all that goes in within, play it back. Hiroaki's good friend, 岩清水 (Iwashimizu) experienced a few incidents with him as they set out to unravel the mysteries. At the end, he's also the one who made me realize that I choose to read this as Hiroaki and Yuiko reunited in death rather than have her be alive in a parallel universe.