Blackout - Guren Maiden Dominate the Succubus Dungeon Ver.1.1 (eng) - Adult Sex Game

Machine translation

A dungeon gate suddenly appeared in the schoolyard of the school. The dungeon gate was connected to a
dungeon controlled by Succubus, and only students could enter.
The strongest students of the school selected there to challenge the succubus dungeon.
However, in towns and slums, changes appear in the people who are exposed to the miasma of succubus.
And that was no exception to the main characters.