In the dark age of humanity, lots of warfare happened in different region, the war took place in the blue planet similar to earth. The terrain itself is very different where 74% of the surface is covered with waters, instead of tanks or any ground army, every nation used ship and planes as a weapon for war, the biggest warzone occurred at the border of 4 nations (Sakura Empire, Eagle Union, Royal Navy, Iron Blood). These nations tried to expand their territory in the middle of the border, due to the large-scaled war humanity was doomed to perish, the beautiful blue sky become a dark grey.

Suddenly, an unknown entity appeared in the sky where the biggest warfare happened, a loud silence was heard in the battlefield, someone tried to make contacts with the unknown entity but before they it tried to make contact with it, a lots of portal appeared behind the entity. Everyone were so scared because what happened is a disaster, tons of unknown humanoid figures were flying above them. The humanoid figure gave an eerie presence, they got a large weapon flying behind their back, what happened after, was a massacre...

Siren, is what the surviving humans called them, a creature that emerged from unknown that took over about 90% of the sea, a creature that is very intelligent and smart. Every nation agreed to do one thing and its to make the Siren disappear from the world, an organization called Azur Lane were created inside their agreement, an organization that will research about the technologies the Siren has and how to make use of them.

Humanity struggled to survive years by years, but then they created something. A cube shaped item has been created, a technology far surpassing what humanity has, they called it Wisdom cube. This cube could construct part of ship as the main ingredient creating KANSEN, a ship that has humanoid figure with their riggings as their weapon and main part, these KANSEN only limited to a humanoid female design, humanity stand a chance against the Siren but its not enough, each commander has perished due to the Siren attack, only 1 commander from Azur Lane remained. This is story of a young man who like to play Azur Lane and got transported to the game, will he achieve his dream? What mystery he will solve in that world? The journey of a Commander who got transported into Azur Lane as their Savior.