Stylish_Demon

"I am an evil god. Would you like to make a contract?"

In "Phantom Heroes Online," a VRMMO where in-game currency can be converted to real money, a man, worn out by society, decides to quit his job and earn a living through gaming. 

In this fantasy world of swords and magic, players contract with advanced AI NPCs, aiding and nurturing them.

The protagonist, Zephyr, whimsically tells a young girl a lie, claiming to be her savior. Believing Zephyr to be the "god who rescued her from despair," the yandere girl transforms into the formidable "Reaper Loli," a top-tier berserker feared as the "Fanatic" across the continent. 

She rises to become one of the game's top players, dominating the leaderboards.

Unbeknownst to Zephyr and the other players, their actions in the game are actually leading to saving of another world.

Dragon Buster II