Hikari no Ou

Touko travels to the capital with a Fire Hunter’s dog after his death.

A past disaster altered human biology, causing instant combustion near natural fire and forcing reliance on bottled lightning harvested from Fire Fiends by elite Fire Hunters. After Touko is attacked by a Fiend, the hunter Haijuu saves her but dies, entrusting his dog Kanata to her care. Her guardians direct her to deliver Kanata and the hunter’s belongings to his family in the capital. Touko joins a collection truck to begin this journey. Simultaneously, in the capital, Koushi grieves his mother’s death while receiving a mysterious letter from the wealthy Okibi family, setting the stage for their intersecting paths.

Touko encounters banished brides while Koushi seeks shelter in the Capital

During a collection truck journey, Touko meets Hotaru, Benio, and Kaho, who were exiled from their villages to remove perceived curses. She also discovers another Fire Hunter in a separate vehicle. Simultaneously, Koushi arrives at the Okibi estate in the Capital, where he meets Youschichi Okibi, an old friend of his father Haijuu. With Koushi’s mother deceased and Haijuu away on Fire Hunter business, Yuoshichi offers housing for Koushi and his sick sister. In exchange, Koushi must research methods to enhance bottled lightning for harnessing volatile skyfire, anticipating government collapse and the need for powerful energy. Later, the caravan stops for refueling and hunting. Kaho tries to escape but is captured by a Fire Fiend. The Fire Hunter and Kanata kill the creature and rescue the girls. However, the truck chief informs Touko that her unauthorized exit violates rules, resulting in her forced removal at the next village.

Koushi meets the Okibi family while the caravan faces a dragon attack

Koushi settles into the Okibi household, meeting Youschichi's daughter Kira and wife Hibana. His sister Hinako is cared for by family doctor Takimi. Youschichi reveals his secret workshop, warning that the rebel group Spiders plans to attack the Capital, causing national collapse. He distrusts the ruling Divine Clans, suspecting they caused a deadly fire to cull the population. Elsewhere, Benio convinces crew member Shouzou to persuade the captain to let Touko remain on the collection truck. Hotoku is dropped off at the next village as the caravan continues. After stopping for fuel, the group is attacked by a massive dragon-like creature.

Dragon Attack and the Legend of the Flickering Flame

A dragon assaults a train, killing Benio and the caravan while forcing Touko, Kanata, Kaho, and Shouzou to flee into the forest. They find refuge with the Tree People, who reveal the dragon is the guardian deity of Kaho's Crystal Village, driven mad by Spider interference. The Tree People promise to escort the survivors to the nearest village. Meanwhile, in the Capital, Koushi continues his skyfire experiments and visits the Central Archive. There, he discovers that only Fire Hunters' sickles can slay fire fiends and fallbeasts. He also learns about the Flickering Flame satellite and the prophecy that its recoverer will become the Lord of Fire Hunters. With no further information, Koushi plans to attend the Boat Festival with Kira and Hinako.

Touko's group encounters Akira, captures Kun, and faces Fiends while Koushi seeks Roroku's help regarding fallbeasts.

Touko’s party reaches a village but is ambushed by Spiders until Fire Hunter Akira and her hound Temari intervene. Akira escorts them to a coastal camp for passage to the Capital, where they capture a Spider child named Kun. Meanwhile, Koushi suffers a nightmare about Hinako and skyfire, then meets Fire Hunter Roroku and his hound Mizore at an Okibi dinner. Koushi expresses interest in fallbeasts, and Roroku offers to include him in a hunt. At the coast, Touko’s group finds the Fire Hunters dead from fire. Kun explains that Spiders use bug venom to resist fire. Fiends attack, injuring Shouzou and forcing Touko to use Haijuu’s sickle to save Kaho. Kun admits the venom failed to protect him, leading to his abandonment. As the group sails to the Capital, a massive whale follows them.

Touko pleads with the tombwhale while Koushi hunts with Roroku in the Capital

Touko and her companions witness the tombwhale, a sea god collecting dead memories. She begs it to spare Shouzou, and it departs. Meanwhile, Koushi joins Roroku in the forest for a hunt. Roroku warns against trusting Okibis and reveals he can use skyfire to blind fiends. They encounter other Fire Hunters interrogating a captured Spider. The Spider breaks free and attacks Roroku, who kills it in front of a shocked Koushi. Touko’s group reaches the Capital and stays with Shouzou’s family while he recovers. The next day, Touko and Kanata go for medicine. Kanata leads them to Haijuu’s abandoned home instead. A policeman confronts them, causing Touko and Kanata to flee and encounter Kira.

Koushi guides Touko to Forbidden District while evading spies for medicine.

Kira assists a distressed Touko, with Kanata escorting her home. Kira informs Koushi about the pair, sparking his interest. Koushi negotiates with Youschichi to let him and Roroku place bottled lightning around the Capital before the Spider invasion. Akira hunts for Shouzou’s medicine, prompting Kaho to propose marriage to care for them. Touko attempts to return Kanata home, while Kun uses an insect familiar to enter a trance. At Haijuu’s residence, Koushi helps Touko and Kanata avoid a spy familiar from the Divine Clans. Touko shares that Haijuu died protecting her and returns his items, providing Koushi closure regarding his father. Spotting a Tree Person, Touko recalls they inhabit the Forbidden District and seeks medicine for Shouzou. Koushi agrees to guide her in exchange for information on Spider fire abilities, unaware they are being followed by the spy.

Touko and Koushi discover the Tree People's origins and the truth about fire fiends in the Capital.

Touko and Koushi travel to the Forbidden District, where a Tree Person guides them to their secret residence beneath the Capital. They learn that Tree People were artificially created by the Divine Clans to aid wild villages. Koushi is also informed that fire fiends are Divine Clan creations, while human fear of fire stems from ancient biological weapons. Upon departing, the pair is attacked by familiars until Akira intervenes and a Divine Clan member halts the assault. Touko returns Kanata to Koushi, who permits her to retain Haijuu's sickle. Back home, Shouzou regains consciousness. Meanwhile, the Tree People discuss the Divine Clans' fear of the Flickering Flame and the Lord of the Fire Hunters, expressing hope that the Flame will destroy both humanity and the Divine Clans.

Koushi and Youschichi test the Lightning Cannon while Akira plans to appeal to the Divine Clans.

Koushi attends a meeting where Akira warns Youschichi and Roroku that the Spiders are attacking collection trucks and wielding fire safely. Youschichi agrees to deploy more trucks to aid villages, noting the Divine Clans are inactive. Later, Hibari of the Wind Clan informs Koushi that the Spiders will reach the Capital in nine days and expresses interest in Koushi and Touko. The following day, Koushi and Youschichi test the Lightning Cannon, a device firing long-range Skyfire shells, which Youschichi intends to use against both the Divine Clans and Spiders. Koushi later discovers Akira and Roroku are close friends and realizes Akira’s brother brought a secret book to the Central Archive. That night, Akira reveals to Touko that the Divine Clans killed her brother for knowing about the Flickering Flame, but she still plans to appeal to them. Touko insists on accompanying her and suggests becoming the Lord of Fire Hunters.

Hinako's Fever and the Divine Clans' Secret Plan

Hinako suffers a fever, prompting Kanata to attack the doctor and Koushi to isolate her. Kira discovers the household is hiding details about Hinako’s condition and confronts them. Hibana drugs Kira, but Hinako attacks her with inhuman speed and strength, nearly killing Hibana before fleeing with Kanata in pursuit. Meanwhile, Touko and Akira travel to the Divine Palace but are intercepted by Hibari. He reveals that Lady Tayurahime is weakening while maintaining protective wards, and the Divine Clans plan to replace her with the Flickering Flame to stop the Lord of Fire Hunters. Touko and Akira refuse to yield, leading to a fight where Kun intervenes. Hibana defeats them, but Hinako saves Touko and Temari before leaving to rescue Akira and Kun. Roroku warns Koushi about Fiends appearing in the Capital, and one attack awakens combat instincts in Touko, allowing her to kill the Fiend with Haijuu's scythe.

The narrative centers on the Lunar Sickles.

The sound of thunder is loud and fierce

The Great Tree

The fire that was banked

The narrative centers on the mysterious Sea of Trees

The Divine Palace

The narrative centers on a character described as an empty girl

The narrative centers on the celestial creature known as the Heavenly Beast

A divine female deity is the central subject of this narrative

Lamplight