Apartment 1303 is white, bright and airy with a sheer white curtain blowing from the wind off the
balcony, and is on the 13th Floor of a large building. The view onto the sea is breathtaking, but the
history of the Apartment is shocking. A number of young women have committed suicide by jumping
off the balcony and it is now about to happen again!
When Yuka, a young woman, moves into this beautiful Apartment, she cannot believe her good fortune, however as she unpacks the moving boxes she feels as if someone is there in the room. Yuka shrugs off this feeling knowing her boyfriend will soon be there. As her boyfriend approaches the building he passes a mother and young daughter who live in Apartment 1302. The little girl grabs his arm pulling him and pointing up to the top floor of the building. There he can see Yuka screaming as she comes over the edge of the balcony and falls! In horror he hears the thud of his girlfriend hitting the ground.
A few weeks later, Sayaka Midorikawa moves into Apartment 1303. Her older sister, Mariko, who has chosen to continue living at home with their mother, is proud of her sister renting an apartment of her own. Sayaka's boyfriend, Ryota, and other friends come over to help unpack and celebrate with Sayaka her beautiful new first apartment. During the party, Sayaka enters the bedroom and a mysterious force draws her to the closet. When she returns to the living room, Sayaka behaves strangely with a blank stare. Suddenly, she puts on a scooter helmet, and with deliberate intention runs for the balcony and over the edge. Her friends are stunned and horrified.
At Sayaka's funeral, none of her friends believe this was a suicide and Ryota tells Mariko of the really strange expression on Sayaka's face as she turned and ran to the balcony. Mariko also cannot believe her sister committed suicide, knowing she was very happy and had many plans for her future. Moments later Mariko sees her sister's ghost and thinks Sayaka is asking for her help in uncovering what happened
Mariko goes back to Apartment 1303 to pack her sister's belongings and soon convinces herself something terrible "lives" in the Apartment.
Mariko investigates and soon learns the history of Apartment 1303. Years before, a single mother, recently widowed, and her young daughter had happily moved in. Soon after however, the mother sunk into alcoholic fueled rages, tormenting her daughter Sachiyo. Sachiyo had quietly taken the abuse for years, keeping everyone and everything at a distance, in despair and sadness. The isolated and co-dependent relationship between mother and daughter had with time become more violent until a day when Sachiyo had finally lashed back at her mother and killed her. In her last breath, Sachiyo's mother had retreated into the closet to die. For six months thereafter Sachiyo had carried out with her life as if nothing had happened – but eventually the building Super presented her with an eviction notice. Sachiyo, realizing the discovery of her mother's corpse will mean her arrest, leapt from the balcony to her death.
Mariko seeks out Detective Sakurai to share her discoveries, but there is little he can do than to advise her to move on with her life. Mariko decides instead to return to Apartment 1303 where she thinks her mother has gone to mourn Sayaka. Her mother is not there but…she is not alone!