Deemo's Story:
The game's plot centers around an unnamed little girl that fell from an open trapdoor in the sky, and a black, mysterious character Deemo who, to help the girl return to her own world, plays piano music to grow a special tree sapling sprouting from the piano.[7] As the tree grows, various rooms of the structure opens for the girl to explore. The girl also encounters a person wearing a white gown and mask, referred to as the "Masked Lady", who expresses resentment towards Deemo and the girl trying to grow the tree.
The tree stops growing at a 20-meter height. The girl discovers a stairway through a painting in a side room and walks into the painting with Deemo. The stairway leads to a chamber with another piano covered in thick thorns. As Deemo plays on that piano, large-scale trembling happens in the structure, and the tree resumes growth.
The tree stops growing again at the final 50-meter height,
which unlocks a final room from thorns. As the girl and Deemo enter the room, the Masked Lady grabs hold of the girl and the two struggles. Deemo stops the Masked Lady with pats on her head, and proceeds into the room with the girl, leaving the Masked Lady behind.
The final room contains a piano and a hovering platform. Deemo plays more piano music which builds a stairway to reach the platform. When the stairway is full built, Deemo carries the girl up the staircases and raises her onto the platform, then return to the piano to play one final tune. The playable song ends with the message "Goodbye, my beloved sister, Alice.", suggesting the girl's name.
As the song finishes, Deemo is revealed to be a manifestation of Alice's elder brother Hans, and gradually disintegrates. A series of flashback scenes reveals the siblings were involved in a fatal traffic accident, where Hans sacrificed himself to save Alice. Alice bursts into tears as the platform elevates towards the trapdoor. The Masked Lady removes her hood and mask, revealing to be another Alice. Alice then wakes up in a hospital bed, attached with medical instruments. She removes them and rushes to the window only to find that she was in a coma the whole time and that her brother is really dead. She then collapses into tears and nurses rush to her side to try and comfort her.