Nautilus

In the game Azur Lane (碧蓝航线 / アズールレーン), "Nautilus" doesn't refer to a specific playable character, but rather to the submarine type or submarine-related concepts within the game. The game is set in an alternate timeline of World War II, where players command anthropomorphic female ship characters in battles. While there isn't a character named "Nautilus," there are numerous characters designed after historical submarines. Submarines play an important tactical role, capable of underwater attacks and known for their stealth. Thus, "Nautilus" represents this general class of ships, holding a strategic position within the game. Submarines typically require specific equipment and tactics to maximize their effectiveness, and their combat style differs from surface vessels. Players must use submarines strategically according to enemy and battlefield conditions to achieve victory. In conclusion, the Nautilus concept in Azur Lane represents submarines, not a particular character.