Haruka Aihara is an ordinary girl with an extraordinary secret: ever since childhood, she’s had an imaginary friend named Koko — a mischievous, comforting presence who’s always been by her side. But everything starts to change one spring, when Haruka finds herself falling for Sora, a quiet boy in her class who doesn’t even know she exists.
As Haruka’s feelings deepen and her world begins to shift, Koko appears less and less — like a dream fading in the morning light. Torn between the excitement of her first love and the fear of letting go of the one who’s always protected her, Haruka faces the bittersweet truth of growing up.