Manga adaptation launched in November 2020

Amazon Japan is listing the seventh volume of Namiki Tsukiyama’s manga adaptation of Mochimaru Sakaki’s Final Boss Fake-out: The Protagonist Thinks She Killed Me So Now I’m Free! light novels as the final volume. The volume will ship on July 7.
Comikey publishes the series in English and describes the story:
A final boss becomes unstoppable with an RPG money exploit!
The strongest final boss in RPG history figures out a way to get
super rich in his own world! Demon Lord Menas, ruler of the Noa
Empire, finds the Resistance’s forces on his doorstep. While Alex,
a determined, beautiful, blonde young lady stands before him,
he gets this weird feeling of deja vu… Isn’t this just like the prologue
of ‘ResNoa’, the video game he plays in his dreams?! Menas realizes
that he was the final boss of his own world all along! He fakes his
death at the hands of Alex, and seizes his chance at a brand new life
with both hands. Our dark hero takes his world by storm, using
whatever cheat codes he has to protect his newfound freedom!
The BookWalker Global Store also added the series in English to its library.
Sakaki launched web novel on the ncode syosetsu website in November 2019. Tsukiyama launched the manga adaptation on Square Enix’s Manga UP! platform in November 2020.
Source: Amazon Japan