Cover for Revolutionary Girl Utena: After the Revolution volume 0.0

Revolutionary Girl Utena: After the Revolution

a.k.a. Shoujo Kakumei Utena

By Chiho Saito

Viz Media

I don't actually know if this is a sequel to the manga or the anime

Cover for Revolutionary Girl Utena (boxset) volume 0.0

Revolutionary Girl Utena (boxset)

a.k.a. Shoujo Kakumei Utena

By Chiho Saito

Viz Media

Distinct from the anime. Both were written by Kunihiko Ikuhara, but the manga was subject to more editorial meddling.