The discovery of a black crystalline mineral known as Originium has accelerated technological advancement in the world of Terra, with its high energy yield allowing people to demonstrate abilities akin to magic called Arts. Large veins of Originium can naturally be found at the sites of Catastrophes, various forms of natural disasters caused by the mineral itself. However, the usage of Originium comes at a price, as there is a high risk of getting infected with Oripathy—an incurable and highly contagious disease. Because nations subject the infected to harsh discrimination, the oppressed begin a dissident movement. Calling themselves Reunion, the rebel faction mercilessly destroys cities, further contributing to the already calamitous nature of Catastrophes. Rhodes Island, committed to treating the infected and uninfected as equals, is a paramilitary pharmaceutical organization believed to be the most advanced in its research for the Oripathy cure. Unfortunately, the person spearheading the project—an enigmatic figure known only as the Doctor—suffers from amnesia, effectively impeding what might be the only hope for the infected to break free from their chains of despair.

Second season of Arknights.

When the "Sirens," an alien force with an arsenal far surpassing the limits of current technology, suddenly appeared, a divided humanity stood in complete solidarity for the first time. Four countries—Eagle Union, Royal Navy, Sakura Empire, and Iron Blood—formed Azur Lane, paving the way for the improvement of modern warfare, which led to an initial victory against the common threat. However, this tenuous union was threatened by opposing ideals, dividing the alliance into two. Sakura Empire and Iron Blood broke away and formed the Red Axis, and humanity became fragmented once again. As a seasoned and experienced fighter, the "Grey Ghost" Enterprise shoulders Azur Lane's hope for ending the war. But behind her stoic persona hides a frail girl, afraid of the ocean. Even so, she continues to fight as she believes that it's the only purpose for her existence. Meanwhile, Javelin, Laffey, and Unicorn—three ships from the union—stumble upon Ayanami, a spy from the Red Axis. Strange as it may seem, they try to befriend her, but as enemies, their efforts are for naught. Still, they persevere in hopes of succeeding one day. Amidst the neverending conflict within humankind, the keys that could unite a fragmented race might exist: a soldier coming to terms with her mysterious personality and camaraderie between those with different ideals.

In a seemingly peaceful time without looming threats of Sirens or war, shipgirls from different nations live together in harmony. Some girls, such as the destroyers Ayanami, Javelin, Laffey, and Z23, attend school. Others immerse themselves into various other activities, including sports, foraging, training, going to formal parties, or even vying for the commander's attention! But one thing is for certain: the girls will continue to deepen their friendship in the pleasant port of Azur Lane!