You likely never heard about this manga given how it's edgy themes that make Goblin Slayer and Berserk gore more tamed. The full title is "Fukushuu O Koinegau Saikyou Yuusha Wa, Yami No Chikara De Senmetsu Musou Suru" but the rough English translation "The Strongest Hero Craves for Revenge Using Dark Magic to Destroy Them All" with the help of 
If edgy, gore, and revenge stories aren't your cup of tea, better to make a pass on this post. While I won't be disclosing any spoilers, this is a dark story.
Plot:
The Hero Raul finally defeats the demon lord but instead of a Hero's welcome, the kingdom turned against him because now that the Demon Lord is gone, as the Hero became the next possible threat. Burned at the stake and ascended into the heaven. Raul reflected on the circumstances of his demise became twisted with rage and obsession for revenge. He demanded his resurrection from the Goddess of Love who has a a twisted obsession for him. Using the goddess' feelings for him, he came back to life and reawakening his latent dark magic to screw all those that threw him under the bus.
At first I thought this was going to be another Kingdom of Ruin story that was written by edgy kid inspired by their wet dream but it's actually the type of story the same edgy kid would likely write had they grew up a few more years.
Let's get one thing straight here, this is a revenge story without any happy ending in sight. Everyone who did the protagonist wrong (which consists of almost everyone) has it coming.
Raul's actions can paint him a villain but due to the backstories provided per person on his hitlist, Raul became an anti-hero. It's easy to sympathize with his actions at getting back against that wrongfully accused him of doing wrong and those that betrayed him. But we're introduced to character who were supposed to be fighting for the side of justice having a twisted backstories. It seems everyone here kept a lot of skeletons in the closet and beyond saving from hell.
Raul is a man that had a bad day which turned him into Joker that was beyond salvation.
This story isn't really for the people that are extremely sensitive to social issues like slavery, human experimentation, torture, cannibalism, rape and all fucked up violence you can think of because the manga made it abundantly clear during the first few chapters that it's going to be a dark tragedy and the reader should buckle up for the ride. I'd give the author a standing ovation for creating side characters that made me think they mattered a little for a few panels then get offed the next by unfortunate circumstance.
Going into Raul's world, even if there was no demon lord to vanquish, the kingdom was already corrupt and leading covert human experimentations, slave trafficking, and other organized atrocities. The existence of the demon lord was a hindrance to business and empire expansion.
I love the way the characters and panels were drawn with so much dark intent. Some panels could pass as a horror story given how grotesque the characters were drawn.
I'd consider this a revenge saga because the revenge plot I initially thought consisted only about getting at the main antagonists which then proceeded to side characters. It was only when the the concepts of getting revenge at gods that this story became a modern Greek epic.
The moral lesson is probably everyone having a little fucked up parts in the character and even gods are no exception to these flaw. It only takes one action to trigger a catastrophic butterfly effect that screws everyone and these can start with the pursuit of fulfilling one's desires.
While there are no updated translations to conclude the manga, I didn't bother dwelling further if the story got axed and was contented with the cliff hanger ending. Even with a cliff hanger ending, you'll see what's the most likely outcome of this revenge saga.
Thank you for your time.