Yūmei surfaces a black forest, best described as an alien world shrouded by darkness even in daylight, ranging up to fifty kilometers in diameter. It is transformed into a massive predatory, gluttonously-carnivorous being with a mind and will, causing it to "move" over entire areas and towns, and absorb all the blood from the wounds of creatures and people within the area, this absorption effect incrementally increased through its passive absorption of the natural energy in the encompassing environment (these trees in particular being sensitive to them); given the great host of trees spawned, this specific absorption limits the abundance in energy for others to absorb - the natural energy consumed can however, be released in full following the destruction of these trees, collectively or to a lesser degree, independently. Anything unfortunate enough to find itself inside it is collectively attacked by the trees and plants, acting like free-form weapons, from all angles, is completely swarmed and covered within a minute. The air's toxicity depends on the volume of blood that has been spilled within the vicinity, of which at early levels leads to anaemia, coughing and nausea, which gradually becomes worse until the end result is imminent death.
The blood from its victims flows through the forest, causing trees and other vegetation to be dyed with a dark-red coloration resembling an animal's innards. The roots and trees secrete blood as if it were sap, and the forest constantly growls like a bloodthirsty beast.
These trees may explode outward at the user's command, releasing all the natural energy they've absorbed back into the surrounding atmosphere to inflict grievous damage to those caught in the blast radius, which is merely a few meters in all directions for each tree. These explosions are only truly lethal when a great amount of natural energy has been absorbed, hence destroying them early on is the only rational method to limiting their true potential.