Succubers! Dark Covenant

One day, Tachio, an ordinary office worker, is suddenly transported to another world overrun with dark monsters known as Yamimon.
In this strange world, he is attacked by Yamimon, but is saved by the beautiful dark hunter Kurenai, with striking red hair and large breasts.
However, the moment he comes into contact with Kurenai,
he fuses with her special battle suit, Gear.
Thus, Tachio fights alongside her as her suit during battles,
while searching for a way to return to his original world (while being made to take care of everyday things at home).

Our story starts when peace has finally taken hold of the world after the war. The former mercenary and dark elf Fornelia, battle-worn and looking for a place to die, saves a young man named Ruse from a monster attack.

Bounty hunter Tifania visited a remote village to investigate the disappearance of local girls.
There are rumors about the incident related to local wicked activities.
There, crazy villagers and mysterious creatures aiming at Tifania attack one after another.

Heroines who seek revenge for various reasons make wishes to the demon race in order to gain power.
It is your task to assist them in their revenge while gradually corrupting their hearts.

In the peaceful Elf village, Aldos, the main character, bravely fought against the evil dark elf mage, Darius, to keep the land safe. But, after winning, Aldos found out a surprising thing – Darius’s daughter, Kora, really wanted revenge against him and his kin.
The king told Aldos to get rid of everyone related to Darius. Even though Aldos is a good person, he couldn’t hurt the young girl Kora. So, he chose to be kind and let her live. But, this decision started a chain of events that made Aldos regret to spare the young dark elf.