His Obsession Began After Losing Her - Chapter 26: A Year of Shadows

When she woke up, Lake returned to the classroom of the third year. The classmates were in class with swords and sticks, and the teacher became a female Taoist.
The little fat man in the back seat, how to put two big hammers under his chair.
Rick found this to be a global era!

- Description from Uukanshu (translated)

Side story of Kyoukai Senjou no Horizon bundled with the first press release of the 1st, 3rd, 5th and 7th Blu-ray volumes of both seasons of anime.

This side story follows Asama, Kimi and Mitotsudaira aboard Musashi one year before the beginning of the main story, as Asama is considering to create a music band together with her two friends for the next festival in Aki, a territory under the governance of K.P.A. Italia.

Zhou Heng drank too much wine, and woke up to find that he had time-traveled, and there was a beautiful woman lying beside him. Just when Zhou Heng, a bachelor of ten thousand years, wanted to take charge, he suddenly discovered that this woman who had a relationship with him was called Sadako, and she was the Sadako in Midnight Ring.

Sadako is just Sadako, pretty and human, but the memories that come out one after another make Zhou Heng discover that his name is Takeo Saeki, and he is the husband of Kayako in the Grudge of the Great Evil Spirit.

Later, at work, Zhou Heng discovered that his female colleague had a strange identity. The daughter of his client, Mimiko Mizunuma, had always been very interested in him when she came into contact with him.

- Description from novelbuddy