My Stepmom's Daughter Is My Ex Anime's Video Reveals More Cast & Staff, July Debut, Opening Song

The official website for the anime of Kyōsuke Kamishiro and Takayaki's My Stepmom's Daughter Is My Ex (Mamahaha no Tsurego ga Moto Kano Datta) light novel series began streaming the full promotional video for the anime on Tuesday. The video reveals and previews the anime's opening theme song "Deneb to Spica" (Deneb and Spica) by DIALOGUE+, reveals more cast and staff members for the anime, and also reveals the anime's July premiere date on AT-X, Tokyo MX, BS NTV, and BS Fuji.

The new cast members include:

Ikumi Hasegawa as Akatsuki Minami, Yume and Mizuto's cheerful classmate

Nobuhiko Okamoto as Kogure Kawanami, Yume and Mizuto's worldly-wise classmate

Miyu Tomita as Isana Higashira, a girl who interacts with Mizuto based on their common light novel interests

The new staff members include sound director Yayoi Tateishi, sound producer Bit Groove Production, music composer Hiromi Mizutani (Non Non Biyori, Hell Girl), and music producers Pony Canyon and APDREAM.

The cast includes Rina Hidaka as Yume Irido and Hiro Shimono as Mizuto Irido.

Shinsuke Yanagi (Bottom-tier Character Tomozaki) is directing the anime at project No.9. Deko Akao (Komi Can't Communicate) is overseeing and writing the series scripts. Katsuyuki Sato (Fire in His Fingertips -My Childhood Friend is a Fireman-) is designing the characters.

J-Novel Club licensed the light novel series, and it describes the story:

Ah, high school. Is there any better place to start fresh after a horrible middle school relationship? Nope! Not unless your ex ends up at the same school as you and is now your stepsibling. What was supposed to be a sanctuary of peace where I could avoid ever seeing her again has become a living nightmare! Everywhere I look, I see her—in my house, in my school, in my class. There's no escape! She even claims that she's the older sibling. Like hell she is!

But I won't lose to her. After all, I'm the older brother in this new family situation. That's right, we're family now. No matter how much we may have thought we loved each other before, we saw one another's true colors and realized we weren't meant for each other. That's why even though we may keep up a buddy-buddy sibling act for the sake of our parents, things will never go back to the way they used to be.

Kamishiro began serializing the story in the Kakuyomu website in August 2017, and uploaded the latest chapter on August 24. Kadokawa began publishing the story in print volumes with illustrations by Takayaki (Arifureta - From Commonplace to World's Strongest), beginning with the first volume in December 2018. Kadokawa published the eighth volume on February 1.

Rei Kusakabe launched a manga adaptation of the novels in Kadokawa's ComicWalker website in December 2019. Kadokawa published the manga's third volume in May 2021.

Source: My Stepmom's Daughter Is My Ex anime's website, Comic Natalie