Tangerines and Watermelons

"Reincarnated into the World of Magic as a demon, the last thing Davis expected was to grow up right amidst the arms of angels. Ever since the group of philanthropic angels took pity on his miserable birth and adopted him, Davis has been forced to keep his evil identity a secret while he signed in to the system. 
""Ding! The Host has signed in at Angel's Pond, 'The Saint's Halo' is rewarded!"" 
""Ding! Devil's blood activated. Sign in error. 'The Devil's Curse' is additionally rewarded!"" 
""Ding! The Host has signed in at God's Throne, 'Gold's Holy Axe' is rewarded!"" 
""Ding! Devil's blood activated. Sign in error. 'The Devil's Manifistation' is additionally rewarded!"" 
After a thousand years of quietly signing into places in the City of Angels and being rewarded with double the rewards, Davis's true identity finally came to light! Now as a true Devil, Davis had both the world of angels and demons surrendering at his feet!"

EndlessFantasy Translation 

After Transmigrating as a Demon, I've Been Adopted by Angels!

Waynec94

Chubbania_EFT

"Congratulations, host, you have advanced to level 9 cherub!

"Congratulations, host, you have advanced to level 9 chaos demon king!"

At this point, the system's voice stopped.

How did his strength increase so much?

Before this, he was just a lord angel and level 1 demon king.

Now, he was only second to the seraph and the twelve demonic gods.

If it was because he saved the princess that his strength increased greatly, he would have to wait for the princess to be rescued by him.

Davis mocked himself in his heart and looked at Princess Lea in his arms with a complicated expression.

After Princess Lea retrieved her blood, her complexion had almost recovered.

Furthermore, when Davis accepted the sacrifice, she was also affected by it.

Holy Sword and Demonic Sword