Seishun Buta Yaro wa Naichingeru no Yume wo Minai (Dengeki Bunko) [Light Novel]

[Machine Translation] Suddenly, a mini-skirted Santa Claus, who calls herself "Toruko Kirishima," appears before Sakita's eyes. Among the students whom she "gave puberty syndrome" to is Sakita's middle school classmate, Ikumi Akagi. The urban legend "#Yumemiru" is a popular topic of conversation on social networking sites among students, who post their dreams and they become real dreams. Sakita witnesses Ikumi using this legend to help others as a "friend of justice" and learns that her body is being attacked by a poltergeist-like phenomenon. The cause of the phenomenon seems to be the past Sakita...? Hey, Azusagawa-kun. How about we play a game? The 11th installment of the series, which opens a door to the past that had been locked.

突如咲太の目の前に現れた、霧島透子を名乗るミニスカサンタ。彼女が「思春期症候群をプレゼントした」という学生たちのなかには、咲太の中学時代のクラスメイト・赤城郁実がいて―。書き込んだ夢が正夢になる、と学生たちのSNSで話題の都市伝説『#夢見る』。郁実がそれを利用し、「正義の味方」として人助けしている姿を目撃した咲太は、彼女の身体がポルターガイストのような現象に襲われていることを知る。しかもその原因は過去の咲太にあるらしく...!?「ねえ、梓川君。ひとつ勝負をしない?」鍵をかけていた過去の扉をあける、シリーズ第11弾。