青春ブタ野郎はナイチンゲールの夢を見ない (light novel)

A miniskirt Santa appears before Sakuta, calling herself Touko Kirishima. She's been handing out presents--Adolescence Syndrome. And one of the lucky winners is Sakuta's classmate from middle school, Ikumi Akagi. According to urban legend, posts tagged #dreaming are filled with prophetic visions and Ikumi is using those posts to play hero. Sakuta sees the results of this firsthand when he spots her saving someone. But then a poltergeist attacks and apparently this is all the fault of his past somehow?!