The opening theme sounds really catchy—Reina Washio performing "Happily Ever After feat. YU-KA" has an energetic quality that fits the series. Fantasy mystery light novels are always intriguing; combining magic with detective work creates compelling storytelling opportunities. January 8 is coming up really soon—less than two weeks away means fans won't have to wait long. Ashi Productions has been on a roll lately—celebrating their 50th anniversary with quality projects like this and Minky Momo shows their continued relevance.

The upcoming TV anime based on the fantasy light novel series The Holy Grail of Eris revealed a new trailer today that highlights the opening theme for the series, entitled "Happily Ever After feat. YU-KA", which is performed by Reina Washio. The series broadcasts in Japan beginning January 8, 2026, and Crunchyroll will also stream it as part of the winter 2026 anime simulcast lineup.

WATCH THE THIRD TRAILER: The Holy Grail of Eris Trailer 3

Opening Theme

"Happily Ever After feat. YU-KA" performed by Reina Washio

The opening theme is previewed in the new trailer.

Production Staff

Directors: JUMPEI & MORITA

Animation Studio: Ashi Productions

Series Composition/Scripts: Kenichi Yamashita

Character Design: Chie Kawaguchi

Assistant Character Design: Jun Yukawa

About the Series

The original The Holy Grail of Eris light novels are written by Kujira Tokiwa, illustrated by Yu-nagi, and published in Japan by SB Creative and Drecom Media.

Yen Press publishes English language versions of the novel series as well as the manga adaptation with artwork by Hinase Momoya.

Streaming Information

Date: January 8, 2026 Platform: Crunchyroll (simulcast) Season: Winter 2026

Are you excited for this fantasy mystery? What do you think of the opening theme? Will you watch on Crunchyroll? Have you read the light novels? Share your thoughts in the comments below!