Eiko Shimamiya is a featured artist on "Asura", theme song for game app "Shinken!! kai", composed and arranged by Yoshihiro Tsukahara. The song was released digitally worldwide on July 1st, 2019.Asura (feat. Eiko Shimamiya)
Lyrics & Vocals: Eiko Shimamiya
Composition & Arrangement: Yoshihiro Tsukahara
You can buy the song digitally from several services, as listed here
I have to say, I mainly enjoy this song for the novelty factor of hearing Eiko sing a hard rock song.
But it's a nice enough song anyway.