A young Felix the Cat and his baby pals find fun and mischief along their travels.

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!

Two souls, living very different lives, wander alone and isolated in their respective worlds. For nine-year-old Ren, the last person who treated him with any form of kindness has been killed, and he is shunned by what is left of his family. With no parents, no real family, and no place to go, Ren escapes into the confusing streets and alleyways of Shibuya. Through the twists and turns of the alleys, Ren stumbles into the intimidating Kumatetsu, who leads him to the beast realm of Shibuten. For Kumatetsu, the boy represents a chance for him to become a candidate to replace the lord of the realm once he retires. While nearly unmatched in combat, Kumatetsu's chilly persona leaves him with no disciples to teach and no way to prove he is worthy of becoming the lord's successor. While the two share different goals, they agree to help each other in order to reach them. Kumatetsu searches for recognition; Ren, now known as Kyuuta, searches for the home he never had. As the years pass by, it starts to become apparent that the two are helping each other in more ways than they had originally thought. Perhaps there has always been less of a difference between them, a boy and a beast, than either of the two ever realized.

Above a nondescript kitchen counter quietly hangs a bunch of ripe, yellow bananas. Suddenly, one of the slender fruits begins to shake, gently at first but slowly increasing in ferocity until it tears itself away from the rest. With a graceful landing, the long and curvy edible gradually rolls back its golden peels, revealing what lies beneath its firm covering to be something unexpected: a cat! This mysterious feline-fruit hybrid is named Bananya. Carefree and gentle, the adorable creature dreams of one day becoming a luscious bananya bathed in chocolate. Together with his fellow bananya, this kitten cloaked in yellow passes its days without a care in the world, enjoying a rather calm and peaceful existence as it experiences what the world has to offer.