TV-Series
Description
In the anime High School Fleet, the character known as 56 is not a student or an instructor, but a cat. This tabby stray is found by one of the main characters, Akeno, at a pier. After this encounter, the cat sneaks into the bridge of the direct education ship Harukaze and becomes an unofficial but permanent member of the crew, accompanying the girls on their voyage. The character is given the grand and somewhat humorous title of Grand Captain aboard the ship.

Physically, 56 is a noticeably overweight and chubby cat. Despite its heavy-set appearance, it is surprisingly agile and capable of moving with swiftness when the situation demands. The name 56 is derived from the cat’s resemblance to a teacher who once taught at the Yokosuka Women's Nautical School, giving its name an in-universe origin linked to the setting's history.

In terms of personality and motivation, 56 behaves largely like a typical cat, acting on its own instincts and whims. It does not have dialogue or complex goals, but its presence provides a lighter, more endearing element to the bridge crew. The cat’s role in the story, however, extends beyond that of a simple mascot. It proves to be surprisingly significant during a critical incident. Through its natural curiosity and actions, 56 manages to capture a creature known as RATt, an act that leads the crew to discover the cause of a major abnormal phenomenon threatening the ships. For this instrumental contribution to resolving the crisis, 56 is later promoted to the rank of Rear Admiral, an acknowledgment of its accidental but crucial heroism.

The character’s key relationships are primarily with the crew of the Harukaze, especially the ship's captain, Akeno, who is the one who found it and allowed it to stay. While it does not undergo a traditional character arc with personal growth, its status evolves from a stowaway to a beloved and respected member of the crew, culminating in its official promotion. Its notable abilities are not combat-related but include its physical agility despite its weight and its keen animal instincts, which prove more effective than electronic equipment in detecting the RATt and thereby resolving a key plot point.