Rascal Does Not Dream of a Nightingale (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?!