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.

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.

666 years after the extermination of the demon race, the Demon King's daughter, Leona, awakens and resolves to execute the "Demon Instrumentality". This plan involves seeking powerful genes across various nations, engaging in reproduction, and giving birth to potent hybrid offspring to dominate these nations, ultimately spreading demon influence across the world.
 
Dark Lord Leona is a fast-paced card strategy game where you strategize and combine your playstyle each turn to crush your enemies.