The newcomers have joined the four nations which are the Eagle Union, Royal Navy, Ironblood, and Sakura Empire. Each of them is getting along and training every day.

In this time, the four nations decided to collaborate and support the "Joint War Game."

Each of the participants will raise their fighting spirits before the grand event in which a few selected members are only chosen to take part.

…How did the Joint War Games come to be held so quickly?
…Who is pulling the strings behind the scenes?

With some mysteries, encounters, and greatly hidden ambitions, a new naval battle never before realized is about to unfold!