Before the night comes down is the fourth bonus side-story chapter written by Iori Miyazawa exclusively for the fourth volume of the Otherside Picnic manga adaptation.
The side story starts when Kozakura accidentally came to the Otherside with Sorawo. While they were walking to the skeleton building, Kozakura wonders for a moment about how the buildings in the Otherside look like they weren't made by humans, but her fear kills all her usual curiosity about these kinds of things. She remembers the time Satsuki took her here and she was too scared to move. After that, Satsuki found herself a new partner, and Kozakura understood that she was no longer qualified to be by her side.
Kozakura then hears Satsuki's voice call her, goes into a weird state, and follows it. When she wakes up from her trance she finds herself standing in the middle of an abandoned town. She remembers when she asked Satsuki what makes the Otherside dangerous at night, Satsuki answered that if Kozakura saw it she would die from fear, but it was also beautiful and she would love for them to see it together. Kozakura sees Sorawo but she doesn't seem to be able to see her, Kozakura chases Sorawo around while shouting at her until Sorawo finally realizes she's there.