Blue Reflection: Second Light

Summary (source: IGDB)

Blue Reflection: Second Light follows Ao Hoshizaki, a girl who attends summer school for supplementary classes and becomes lost in an unknown world. She meets three girls — Kokoro Utsubo, Yuki Kinjou, and Renya Miyauchi — who have lost their memories and live in an isolated school surrounded by water. One day, a path and portal leading to another world appears and the girls decide to go through it. They eventually come across a monster and unlock a power that lets them fight back. In addition, Blue Reflection protagonist Hinako Shirai will appear in the game having also lost her memories.