Stairway of Time

To escape her exhausting daily life and definitively bury her past, she chose to marry the first comer. But, one night, as she takes a mysterious staircase in her old high school, she is propelled 14 years back, into her high school body. Is this a dream or reality? If she's really come back to the past, then she knows what to do: never meet her childhood sweetheart! Because this guy is the one who broke his life...