A New Chapter Begins with a Double Tie-Up Single!

Eir Aoi’s new song “Unrealistic” has been selected as the opening theme for That Time I Got Reincarnated as a Slime Season 4.

“Unrealistic” is an intense rock number built around a full band sound that matches the epic scale of the Tensura story. Be sure to check out Eir Aoi’s evolving sound as she begins a new chapter with Lantis.

A CD featuring “Unrealistic” is set for release on April 22, 2026. This CD will also include “MONSTER,” the opening theme for Classroom of the Elite 4th Season: Second Year, First Semester, making it a double tie-in single.

Comment from Eir Aoi

 

When I learned that I would be performing the opening theme for That Time I Got Reincarnated as a Slime, a series loved by fans all over the world, I was truly surprised. More than anything, I couldn’t contain my excitement.

 

“Unrealistic” is an intense rock number that matches the epic scale of the story. I hope you’ll enjoy it together with the anime.

Product Information

“MONSTER,” OP theme of Classroom of the Elite 4th Season: Second Year, First Semester / “Unrealistic,” OP theme of That Time I Got Reincarnated as a Slime Season 4

Release Date: April 22, 2026

Formats:

Artist Edition Tracklist

1. MONSTER

Lyrics: Eir

Composition/Arrangement: GAK-amazuti-

2. Unrealistic

Lyrics: RUCCA

Composition/Arrangement: Ayato Shinozaki, Ryosuke Tachibana

3. DRUM

Lyrics: Masami Kakinuma

Composition/Arrangement: yoma

4. Decay

Lyrics: Eir

Composition/Arrangement: Ryo Maruta (Arte Refact)

5. MONSTER (Instrumental)
6. Unrealistic (Instrumental)
7. DRUM (Instrumental)
8. Decay (Instrumental)

Classroom of the Elite Edition Tracklist

1. MONSTER
   2. Unrealistic
   3. Decay
2. MONSTER (Instrumental)
3. Unrealistic (Instrumental)
4. Decay (Instrumental)

TenSura Edition Tracklist

1. Unrealistic
2. MONSTER
3. DRUM
4. Unrealistic (Instrumental)
5. MONSTER (Instrumental)
6. DRUM (Instrumental)

Profile

A Japanese singer-songwriter who has earned passionate support from anime fans both in Japan and overseas for her powerful, soaring vocals and exceptional expressive range. Her music is marked by emotionally stirring lyrics and melodies, as well as dynamic live performances.

She has successfully performed four times at Nippon Budokan and appeared at Yokohama Arena, in addition to staging concerts in 15 countries and regions worldwide, including in Paris, London, Shanghai, and San Francisco. She continues to enjoy a strong international fanbase.

Official Website: https://aoieir.jp/

X: https://x.com/eir_ruru2

Instagram: https://www.instagram.com/aoieir

Copyright:

©Taiki Kawakami, Fuse, KODANSHA/ “Ten-Sura” Project

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