Jain no Ikenie 2 ~Onna Yuusha to Shuudoujo - Hateshinaki Zecchou & Shokushu Jigoku ni Ochita Dark Elf to Seijo~

At some point, the Tentacle Princess, Altea, began ruling the world, spreading terror and despair.
But a girl received a divine oracle to defeat her and save the world.
Her name is Rigel, the Hero.
Alongside her battle sister, Capella, Rigel sets off into the deep forest where Altea’s castle is said to be.
Unaware that a trap of humiliation and depravity awaits them…

[Translated from dlsite]