Spirits (精霊, seirei) are incorporeal entities that are most typically tied to nature, a person's soul, or the afterlife. Spirits may take on many various forms, depending on the type. Some are harmless, and can even be collected, whereas others may attack for no reason. If a spirit is strong enough, it may possibly possess the body of a living enemy.
It is known that absorbing a spirit from a living individual will shorten their lifespan, dependent of how much is taken.
Spirits in Len'en Project
One type of spirit is known for their hollow, sullen expressions, and wearing hitaikakushi on their heads. They are regularly aggressive, attacking almost anyone they encounter.
The second type is a harmless variant, appearing to have no will of its own. They are smaller, and resemble an orb with a yellow or orange core. They may be collected and dealt with however the owner pleases. This may range from selling to an interested merchant (ex. Kuroji Shitodo), or absorbed to become stronger (ex. Shion and Sese Kitsugai).