"Dark Water" is a psychological horror manga that explores themes of isolation, guilt, and the supernatural. The narrative centers around a young woman named Yoshimi, who moves into a dilapidated apartment complex with her daughter, Ikuko, following a bitter divorce. The building is plagued by persistent water leaks, creating an oppressive atmosphere of dampness and decay. Yoshimi struggles to rebuild her life while caring for her daughter, but strange occurrences begin to disrupt their fragile peace.

The story takes a sinister turn when Ikuko starts exhibiting odd behavior, claiming to see and interact with an imaginary friend. Yoshimi initially dismisses these incidents as the product of a child's overactive imagination, but the situation escalates when she discovers that the apartment complex has a dark history. Years earlier, a young girl named Mitsuko drowned in the building's water tank, and her spirit is believed to haunt the premises. As Yoshimi investigates further, she uncovers unsettling connections between Mitsuko's death and the eerie events unfolding around her.

The tension builds as Yoshimi becomes increasingly paranoid, questioning her own sanity while trying to protect Ikuko from the malevolent presence. The water leaks, initially a minor nuisance, take on a more ominous significance, symbolizing the encroaching threat of the supernatural. The narrative delves into Yoshimi's internal struggles, her feelings of inadequacy as a mother, and her guilt over the divorce, all of which are amplified by the haunting.

The climax reveals the full extent of Mitsuko's influence, as her spirit seeks to claim Ikuko as a replacement for the life she lost. Yoshimi must confront her deepest fears and make a desperate choice to save her daughter, leading to a resolution that is both tragic and hauntingly ambiguous. The story leaves lingering questions about the nature of the supernatural and the psychological toll of unresolved trauma.

The main characters are Yoshimi, a determined yet vulnerable mother; Ikuko, her innocent but increasingly affected daughter; and Mitsuko, the vengeful spirit whose presence drives the narrative. The apartment complex itself serves as a central element, its deteriorating state mirroring the emotional and psychological unraveling of its inhabitants. "Dark Water" is a chilling exploration of maternal love, loss, and the thin boundary between the living and the dead.