Houkago Saitensei!

Vol.3 Chapter 17.1: Pixiv Extras
Vol.3 Chapter 17: Reach for the stars (Those who reach out to the stars)
Vol.3 Chapter 18: Once Again, In An Everyday (Other)World
Vol.3 Chapter 17: Reach for the stars (Those who reach out to the stars)
Vol.3 Chapter 18: Once Again, In An Everyday (Other)World
Ten years ago, a magic circle suddenly appeared above Earth, connecting it to the parallel world Alterna. This led to the invention of the Alternaphone, which allows people to freely reincarnate between worlds, allowing earthlings to become adventurers and otherworlders to become normal citizens. The series follows two amnesiac girls, earthling Kurami Utaho and otherworlder Melua Solaris, as they go back and forth between ordinary life on Earth and adventuring on Alterna. Published in Manga Time Kirara Forward