Reiryoku

Reiryoku (霊力^?. lit. "Spiritual Power") is an energy that fuels the powers of each Spirit. Every Spirit is ranked differently in regards to how much Reiryoku they possess.

Usage

Reiryoku is the fuel that helps create a Spirit's Astral Dress and Angel. If any of those two are damaged, Reiryoku can be consumed to restore both to optimal condition. The use of both also releases Reiryoku into the surrounding environment. Tohka Yatogami and Mio Takamiya have been shown capable of deploying barriers made of Reiryoku to protect themselves from attacks. However, a Spirit's Reiryoku is not inexhaustible. Much like stamina, a Spirit that has used up all her power is liable to collapse from sheer exhaustion. As the Spirit of Origin, Mio's Reiryoku is immense. By splitting portions of her power, she was able to use her Reiryoku to create the Sephira Crystals. However, even Mio notes that her power is finite and there is a limit to the number of Sephira Crystals she can create.

Detection

Reiryoku can be detected as Reiha (霊波^?. lit. "Spirit Waves"). Both Ratatoskr and DEM have airships equipped with instruments that allow them to gauge a Spirit’s Reiryoku levels. This can be used to determine a Spirit's identity and location, but it becomes nigh undetectable for a sealed Spirit and only gives a weak signal when they manifest their Limited Astral Dress (限定霊装, Gentei Reisō^?). Inverse Spirits have their Reiryoku readings plummet to negative values, which sets off a Category E alarm within Fraxinus.

Sealing

Shido losing control of his powers.

When a Spirit is sealed by Shido Itsuka, a Path (経路パス, Pasu^?. lit. "Route") of Reiryoku is formed between them. The Spirit becomes much weaker, only able to summon a Limited Astral Dress that meshes with their current outfit, but the Reiryoku will backflow under emotional distress. The Path can naturally correct itself, but if the Spirit regains their full power, they will need to be resealed. If the Paths grow too narrow, the Reiryoku will build up inside Shido, granting him strength on par with a Spirit at the cost of also providing an intoxicating effect that lowers his inhibitions. Eventually, the buildup will cost him his sanity, turning him into an uncontrollable berserker and cause a catastrophic explosion if the Paths are not reopened. Conversely, the Paths narrowing also restricts the sealed Spirits' access to their powers, forcing them to budget their remaining Reiryoku, as running out would mean a complete lack of access to their powers.

In the case of Nia Honjo losing most of her Sephira Crystal, Shido was able to save her life by sealing her, which healed her with the resulting path sharing Reiryoku between them. However, despite this helping Nia, she still needed intense medical care from the Realizer in order to fully stabilize her condition. Additionally, Nia's condition left Rasiel in an unusable state and despite technically sealing Nia, Shido didn't have access to this Angel until after sealing Kurumi Tokisaki, who had by then taken back Rasiel's Sephira from Westcott. Nonetheless, Nia's circumstances allowed her favorability of Shido to help seal the Nibelcole regardless of the pseudo-Spirits' personal feelings towards Shido, as the <Nibelcole> are a creation whose power source was derived from Nia.

As the Spirit of Origin, Mio is able to freely regulate the flow of these pathways. During her first fight against Tohka, she was able to close up the pathways to prevent Tohka from fully regaining her powers. Likewise, she was also able to utilize this administrative ability to help stabilize Shido's condition after he was overheating from Reiryoku due to the pathways narrowing.

List of Ranks

Numerical Value	Spirits	Notes
125	Tohka Yatogami
199	Yoshino Himekawa
220	Kurumi Tokisaki
215	Kotori Itsuka
210 (244)	Rinne Sonogami	Stats in parenthesis are numbers in the Utopia world.
179	Kaguya Yamai
185	Yuzuru Yamai
159	Miku Izayoi
219	Origami Tobiichi
201	Tenka
180	Natsumi Kyouno
242	Inverse Origami
178	Maria Arusu
165	Marina Arusu
45 (230)	Rio Sonogami	Stats in parenthesis are numbers in the Utopia world.
142	Nia Honjo
205 (225)	Mukuro Hoshimiya	Stats in parenthesis are when using Shifuru.
56	Nibelcole
204	Yamai Kazamachi
502	Beast
999	Mio Takamiya

Neighboring World

Due to the Neighboring World being compromised entirely of Reiryoku, Reiryoku is crucial for the survival of the Quasi-Spirits living there. A Quasi-Spirit that has completely exhausted her supply will gradually fade away before vanishing completely. Additionally, there are various ways of generating and gathering ambient Reiryoku from the environment. In the Ninth Region Yesod, this is done through holding idol concerts and singing, which circulates a flow of Reiryoku between idols and their fans.

Furthermore, those within the Neighboring World can create various items out of thin air through using this power. Versatility in this construction ability is based on supply level and imagination, which means psychological limits can be an impending factor. For example, Furue Tonami notes that it is easy to create classroom items when in a classroom, but the creation of weapons there would be more difficult since weapons naturally feel out of place in a classroom.

Trivia

• The kanji for power (力) is used when described the world's mana gathered to create Spirit of Origin and what she dissolved back into after fading away.