Episode 1 (Hanyō no Yashahime)

Inuyasha: Since Then is the first episode of Hanyō no Yashahime.

Synopsis
A young half demon named Towa was told a tale from around eighteen years prior about a a half demon and a priestess who battled demons.

Summary
Inside a castle, in the middle of the rain in the Sengoku Era, a mysterious girl named Towa Higurashi in clothes from the future is captured and being interrogated by the shogunate adviser from who calls her "Hanyō Princess" and who comes from a village called Reiwa Era. He asks the girl about her origin by showing her a book that contains data on the history of Japan. Towa is scared and restrains herself to avoid revealing any information since it could alter the course of history and therefore the future could be affected.

At that moment, a subordinate of the shogunate adviser brings in a box what he claims is the steel carriage that a mysterious young woman brought from a village called Tokyo ten years ago. Towa is surprised to see that that object was the worn seat of a bicycle, which provokes the reaction of the shogunate. Then, the shogunate's adviser decides to tell Towa about an event that occurred eighteen years ago.

The story then flashes back to six months after nineteen-year-old Kagome started living with Inuyasha and her other closest friends and their young children, two of which are identical twin sisters. Gyokuto and Kin'u were interested when Kagome told them how effective the Kikyō root was, but they wished it was a snack instead.

Inuyasha and Miroku went to investigate these death in a field. Miroku sensed something nearby and threw his sutras around the field. The yōkai rose up from underground. The villagers were shocked to see that it was carrying the heads of its victims Inuyasha attacked it with Tessaiga but it escaped. Miroku asked the villagers to take him to where the yōkai was originally sealed.

It soon killed some roaming bandits and fled. Kohaku arrived later with Kirara and was unsure of what happened. Sesshōmaru showed up and stated that this yōkai was worthless but persistent. Inuyasha and Miroku learned from Kaede that Ne no Kubi had been sealed by Kikyō after they found one of her arrows where it was first sealed. It broke into Miroku and Sango's house and attacked Kagome. It thought that she was Kikyō and demanded the Shikon no Tama from her (Ne no Kubi was unaware that Kikyō was no longer alive and that the jewel disappeared from the world after the death of Naraku due to it being sealed for so long) Sango pushed it back with Hiraikotsu. Inuyasha arrived and tried hit hit it with Tessaiga, but it escaped underground again. Kagome, Inuyasha, and Miroku were prepared to stop it before it killed everyone in the village for nourishment. Some of its roots suddenly appeared in front of Inuyasha while he was carrying Kagome. Kagome shot at them with her arrow and Inuyasha hit to with Tessaiga, but there were too many roots. It also attacked some more villagers, but they were saved by Kohaku. Sango decided to fight as well and left Kohaku to look after her son.

Ne no Kubi was proving to be trouble due to more of its roots spreading. Kagome told Inuyasha to let her down so she could follow the roots to its main body since they were after her. The two of them suddenly saw a flash of moving forward. It came from Kaede shooting the arrow that Kikyō used to seal Ne no Kubi. Kagome arrived where the arrow landed since it would lead her to the yōkai true form. When she arrived to the arrow's location, Ne no Kubi tried to devour her as it emerged from underground. Inuyasha arrived just in time to save her. It true from was revealed to be a gain mass of roots with various eyes. It still thought that Kagome was Kikyō and told her that he would devour the Shikon no Tama. Kagome told it that she was not Kikyō and the Shikon no Tama no longer existed. In the end, with the head wounded by Kagome's Sacred Arrow, it was eliminated by Inuyasha's Wind Scar.

However, one of its roots had managed to survive carried by Yotsume and had parasitically attached itself to the Goshinboku, allowing the yōkai to gain the ability to open up a portal through from Sengoku jidai to Modern era.

Back to Towa, she is rescued by a demon slayer named Setsuna and a demon bounty hunter named Moroha, who realize that the lord attendant is a demon as well and chase after it but before departing, Towa confiscates the book and the seat from the lord.

Differences from the manga

 * The names of Miroku and Sango's children are not revealed in the manga.
 * The manga did not feature the yōkai Yotsume that secretly watched Inuyasha, Kagome and their friends as they fought against the awakened Ne no Kubi.
 * Ne no Kubi's defeat was slightly different in the anime and the manga. In the manga, Ne no Kubi was seriously wounded by Kagome's sacred arrow and destroyed forever by Inuyasha's Kaze no Kizu. In this episode, after their combined attack, Inuyasha uses Meidō Zangetsuha which sends the demon to the netherworld.

Error

 * Kaede stated Kikyō had sealed the Root Head before meeting Inuyasha, but then stated it was around the time she helped the bandit Onigumo, who was however found and treated by her after being severely injured by Kansuke and thrown off a cliff for having tricked him into attacking Kikyō, hoping that Inuyasha would kill him.

Episodi 1 (Hanyo no Yashahime) Episodio 01 (Hanyo no Yashahime)