In a distant future where the sun no longer shines, Toshiro Kamiya gives up his body to a sinister floral metamorphosis for a payday.

The earth of the distant future is covered in thick clouds, and the sun no longer shines. Plants wither, and oxygen is thin. To fight extinction, humankind has developed a technology that turns humans into plants, providing a small amount of oxygen. Is this process sustainable? Is it ethical? Toshiro Kamiya must consider these questions as he’s faced with a difficult choice—save his family or save himself.

Kamiya is trying to make the most of the time he has left before completing his spiriflor transformation. But when he’s attacked by a mysterious spiriflor that somehow remains capable of humanlike movement and functioning, his childhood friend Hourai becomes one of the creature’s victims.