Towa Higurashi learns about an incident that took place decades ago involving a half demon named Inuyasha and a priestess named Kagome.

The truth behind the night that sealed the fate of Towa, Setsuna, and Moroha’s parents is finally revealed.

Jaken recalls that fateful day fourteen years ago, when Zero placed a curse on Rin that would make her slowly rot away to an excruciating death. The three girls search for Bokusen-Oh, who may have a lead on the whereabouts of Towa’s new weapon.

The three girls arrive at Mount Musubi but are trapped by a powerful barrier. Moroha manages to escape and runs into something unexpected.

Moroha and Takechiyo strike back against Shogen Mamiana. Setsuna experiences her first New Moon. Towa is trapped by Nanahoshi’s eternity bugs.

Zero unearths Towa’s sadness about growing up in the modern world and corners her with her memories of loneliness and suffering. Sesshomaru appears before the demon slayers and commands Setsuna to pay the Tree of Ages a visit.

Towa is consumed by rage and loneliness. Setsuna tries to stop her from killing Zero because the curse on their mother cannot be lifted unless Zero lets go of her regrets. Sesshomaru gives Moroha the Black Pearl.

Kirinmaru takes the Black Pearl from Moroha and demands that she bring Akuru to him. Towa and Setsuna try to lend a hand, but Sesshomaru arrives at the scene to take on Kirinmaru instead. Meanwhile, Rion and Riku head to Mount Musubi.

Inside the Black Pearl, Moroha is finally reunited with her parents, Inuyasha and Kagome. Inuyasha begins to see a way out of the Black Pearl. Meanwhile, Kirinmaru’s attack leaves Sesshomaru gravely injured.

Wanting to prove his strength, Kirinmaru faces off against Sesshomaru. Towa summons the Tenseiga. Shippo waits for Inuyasha and the others at Gozu and Mezu’s gate.

In the present day, Osamu Kirin sees the Grim Comet approaching. Meanwhile, in the feudal era, Towa’s life is in danger after she uses her Zanseiken. The Spirit of the Tree of Ages orders the half-demon princesses to go destroy the Grim Comet.

To destroy the Grim Comet, Towa, Moroha, and Setsuna must travel to the present day using the Windmill of Time, but Meidomaru stands in their way. Kirinmaru takes Rion and tries to travel across time by force.

Inuyasha and the others have their hands full with the evil spirits pouring out of the burning Windmill of Time. The three girls and Osamu Kirin try to stop the Grim Comet from falling to the earth.

Osamu Kirin brings the Grim Comet to the feudal era. He convinces Rion that they are both hoping for the same world and promises to make it a reality. Meanwhile, Towa, Setsuna, and Moroha are stuck in the present day.

Towa, Setsuna, and Moroha must save Rion, who has linked her fate with the Grim Butterfly, but Osamu Kirin stands in their way. Kirin declares that he and Rion should reign over the world in order to bring about true peace.

Setsuna directs Towa and Moroha as they continue to sever Rion’s threads of fate. Each time a thread is severed, more of Rion’s true feelings are revealed. As Kirinmaru fights Sesshomaru, he realizes the real reason he lost Rion.

The feudal era is saved from the Degenerate Age. Inuyasha helps repay Moroha’s remaining debt. Towa and Setsuna receive kimonos from their mother, Rin. Towa, Setsuna, and Moroha accept a demon-slaying request from a mysterious man.