If you're looking for anime similar to Kan Colle: See You Again on Another Quiet Blue Sea, you might like these titles.
The crew of the Harukaze relax after midterm exams, and a Coco receives a new mission.
Akeno Misaki and Moeka China share one goal—to join the Blue Mermaids! A group of fierce women, the Blue Mermaids are key to keeping peace among the seas and coastal cities in this age of maritime trade. To be a part of this elite group of sea protectors, they must succeed at Yokosuka's Marine High School. Akeno and Moeka, together with their classmates, will take the plunge to become Mermaids!
In a trashy bachelor pad lived a colony of roaches who are able to roam freely for food or for games. Because of the homeowner being gentle with the roaches, they have no fear of traps, spray, or being stepped on. However when the homeowner starts bringing over a woman over, life starts to change for the roaches who are already living an easy life.
Azur Lane, a combination of all the different Camps in the world, was once successful in repelling the underwater menace, the Siren. Now splintered, they must face a new threat in Red Axis, former allies who crave to wield this otherworldly Siren technology for their own nefarious desires! Who will be victorious in the never-ending war between these battleship girls!?
The Nation of Gallia has always remained neutral in conflicts and has only gone to war to defend itself. However, as war flares between the East Europan Imperial Alliance and the Atlantic Federation, Gallia is soon targeted for its abundance of ragnite ore, a versatile and hugely valuable material. The Civilian Militia is soon called into action, and Welkin Gunther - son of a legendary war hero - is named leader of Squad 7. Under his command are the headstrong and practical Alicia Melchiott; the sharp-tongued Brigitte Stark; the grizzled veteran, Largo Potter; and Welkin's adopted sister Isara, whose Darcsen heritage means she faces prejudice, even from members of her own squad. With the rest of Squad 7 and the mighty tank Edelweiss, they must do their best to defend Gallia.