You are Kagami Kouhei, the average son of adopted parents, whose greatest concern is maintaining the status quo of your carefree student lifestyle. Your days pass uneventfully, accompanied only by the rhythmic sound of a train rushing down its track. You hear it in moments of stillness, powerless as it carries you away to an uncertain future... But into your life come three women who threaten to disrupt the fragile balance you so carefully guard, promising to take you places you've never been, with experiences that might just change you forever...