Hikari works at a design office. Her upbringing is not a wealthy one, but now she has a good job and an affectionate fiancé, Kōta. She is happy and feeling very much fulfilled. But, when she happens to see her ex-boyfriend Shin, once the love of her life, her relationship with her fiancé starts to fall apart… Hikari and Shin used to work for the same design office, where he was her boss. They had been lovers, but, one day, all of a sudden, Shin left her without a word. Now, he is married to Ran. Ran's over-possessive manic love towards Shin makes her consumed with jealousy against Hikari. And Hikari's fiancé Kōta also finds himself suffering from his love and his jealousy… Shin's presence is driving him slowly but steadily to the brink of insanity.