Once Upon A Time, there lived a Princess and a Knight.
Both were destined to save the Kingdom of Hyrule from certain demise. They, alongside four chosen warriors, were well prepared for Calamity. And yet... four years passed after the pulling of the sword. Many wondered if this prophecy of apocalypse was simply fiction. During this time, the Knight and Princess wedded and had two children, Lily and Hyden Bosphoramus. But on the day of their son Hyden's birth, that Calamity struck. Hyrule was taken by surprise, all four champions, Mipha, Urbosa, Revali, Daruk including the King were killed.
In an attempt to save her husband and children. Princess Zelda, unlocked her power and temporarily sealed Ganon away in the Castle. Prince Link, alongside his children were kept in the chamber of resurrection until their fatal wounds healed.
When he awoke, he vowed to protect his children from Calamity Ganon and train his daughter until she herself could unlock her promised sealing powers and seal Ganon. Only Lily, his only daughter, could seal Ganon away. For he was sure his wife was dead. And only he could defeat Ganon. For he was sure he was the only one to hold the sword.
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!]