The theme of unity could also be present. When faced with the threat of the sea monster, the people of Tokyo from all walks of life - from the business district to the fishing villages - might have to come together. They would need to put aside their differences and work towards a common goal of protecting their city from the sea monster.
I'm not sure of the specific 'Tokyo and the Sea Monster' story. It could be about a sea monster attacking Tokyo, perhaps like the classic monster movie scenarios where the sea monster emerges from the ocean and causes chaos in the city, with the people of Tokyo having to find ways to defend themselves.
Another theme could be difference or alienation. If the sea monster is different from other sea creatures, it shows how being an outcast can lead to a lonely life. It might also touch on themes of self - discovery as the sea monster tries to figure out its place in the ocean world.
One possible theme could be self - discovery. Just as Cinderella found her true self when she transformed for the ball, the Tokyo girl might also go through a process of realizing who she really is. Another theme could be the power of dreams. Cinderella dreamed of a better life, and the Tokyo girl may have similar aspirations in the context of the big city.
One possible theme could be fear. Since there's a monster involved, fear of the unknown or the dangerous is likely.
They could live happily ever after, finding a peaceful corner of the ocean to build their family. Maybe they would have little sea monster babies and teach them all about the beauty and danger of the ocean.
One possible theme could be isolation. As a nameless girl in a big city like Tokyo, she might feel alone and isolated in the crowd.
One possible theme could be the power of love in a big city. Tokyo is a huge metropolis, and love can be both a refuge and a source of strength in such a busy place.
Some common themes include the struggle between the new sea monster self and the old human self. There's a constant internal battle of identity. Adaptation is another theme. The transformed character has to adapt to the new underwater environment, different from the human world they knew. And there can be a theme of revenge. If the transformation was due to some unjust act done to the character, they might seek revenge as a sea monster, using their new powers against those who wronged them.
The Loch Ness Monster is also well - known, although it's more associated with a large lake rather than the open sea. But it has the characteristics of a sea monster. People claim to have seen a long - necked, large - bodied creature in Loch Ness. There are also tales of mermaids, half - human half - fish beings. They were often depicted as luring sailors to their doom in some stories. And in some Scandinavian legends, there are sea serpents that were supposed to be enormous and dangerous.
One possible theme could be fear of the unknown. Since the monster has no name, it represents something that is not clearly defined, which often scares people.