Original story, not my art.
*DISCLAIMER* This story may contain, drug use, alcohol use, smoking, violence, language, and sexual content. It may contain sad backstories, so this is your full Trigger Warning (TW). I'll try to warn you with a TW before sad stuff. If you do not like this, don't read on.
Levi Ackerman is a total douche. He acts like he's better than everyone else (granted, he is). One day his car breaks down and Eren, owning his dad's business, 'fixes' it. After coming back regularly, they start to share a connection.
Transmigrated into DxD World-Kuoh Town, Hibari Kyoya. an average student, spent 18 agonizing years in the world fully aware of the dangers, knowing he is utterly powerless in a world of gods and monsters, Until...
[Ding! Sign-In System loading... 20%... 50%... 80%... 100%.]
Destiny, it seems.. has a cruel sense of humor. A [Sign-In System], long overdue, finally bursts to life within him, offering a chance at survival, a chance at power...
[Ding! Congratulations! You have received the Rainbow-Grade Gift Bag!]
...
He then started completing System's tasks, accumulating even greater rewards.
[Ding! Task completed. Reward: Perfect Rumble-Rumble Fruit (Weakness to water Removed).]
[Ding! Task completed. Congratulations to the host for obtaining the Flying Thunder God Technique!]