Red River adds Nana Mizuki to the cast as its second cour gets new theme songs

Red River is adding a very recognisable voice to its next chapter. Nana Mizuki joins the cast as Ursula, a false goddess impersonating Ishtar, and she will also perform the new opening theme as the anime moves into its second cour.

Ryu Matsuyama will perform the new ending theme, giving the continuing historical fantasy series a refreshed musical identity alongside its new cast member.

What's actually going on

The official anime website identifies Mizuki’s opening as “Akatsuki no Hoshi”. Ryu Matsuyama’s ending is “flow feat. Yūko Andō”. The announcement also reveals new visual material for Ursula.

Red River, or Sora wa Akai Kawa no Hotori, premiered on NTV’s AnichU block on 7 July at 25:35 — effectively 1:35 a.m. on 8 July — with BS NTV beginning its broadcast on 8 July. Crunchyroll streams the anime as it airs in Japan.

Tatsunoko Production handles animation. Kōsuke Kobayashi directs, Yoriko Tomita oversees series composition and Kenji Fujisaki designs the characters.

Why you should care

A new cour is often where an anime either deepens its identity or starts throwing plot at the wall. Adding a performer as experienced as Nana Mizuki gives Red River both a new character hook and a theme song with a strong chance of standing out.

The key word is “new”, not “finished”. This announcement does not confirm a release date for a home video, a new international rollout or any game-changing plot development beyond Ursula’s role. It is a cast and music update for an ongoing broadcast.

Our opinion

Nana Mizuki is a major musical get, and pairing her with a new opening makes this more than a routine cast note. If Red River can match the theatrical confidence of its music choices, the second cour has an encouraging launchpad and a stronger identity before the next episode arrives. Existing viewers should keep it on the radar and add the songs when they land, while newcomers still need the series itself to earn the recommendation. The update is worth following, but the performance and story will decide whether the music is foundation or decoration.