They join a previously announced voice cast that stars: 

• • Ami Koshimizu as Lufas Maphaahl
• • Yuri Usui as Dina
• • Yukina ‌Shuto as Aries 
• • Hisako ‌Tojo as Libra 
• • Naoya ‌Uchida as Aigokeros 
• • Mika ‌Kanai as Parthenos
• • Cocoro ‌Omori as Virgo
• • Shunsuke Takeuchi as Alioth
• • Tomoaki Maeno as Megrez
• • Daisuke Hirakawa as Merak
• • Satomi Akesaka as Benetnasch

Yuya Horiuchi (Love Live! Nijigasaki High School Idol Club Season 2 assistant director) is directing the anime series, with Kazuyuki Fudeyasu (Flower and Asura) as series screenwriter and Maiko Ebisawa (Love Live! Superstar!! Season 3 Episode 8 co-dance part animation director) as character designer. Takashi Kobayashi and Shota Ueno are credited as sub-character designers, while Wao World is in charge of the animation production. 

The original isekai dark fantasy light novel series is written by Firehead and illustrated by YahaKo. It was first published by Earth Star Entertainment on February 15, 2016 and concluded on April 15, 2019. Nine total volumes were published in Japan. 

The light novels also inspired a manga adaptation by Tsubasa Hazuki in June 2017. The original Shosetsuka ni Naro web novel began in October 2015 and ended in April 2019.

©炎頭/アース・スター エンターテイメント/野生のラスボスが現れた！製作委員会

J-Novel Club publishes the A Wild Last Boss Appeared! light novel series and manga in English digitally. It describes the main synopsis of the light novels as:

The year is 2800 and Lufas Maphaahl – The Black-Winged Tyrant, Great Conqueror, and leader of the Twelve Heavenly Stars – has returned. A man wakes up in the body of his MMO character 200 years after her defeat during a player-made event in the game, Exgate Online. Now, he’s stuck in her body. But this isn’t a game, it’s real. With her reign long over, and her legacy one of fear, Lufas must journey through the world of Exgate, looking for answers, possible comrades, and all the monsters her “death” unleashed upon the world…