A girl who is part Titan, resembling the Legendary Films version of Godzilla, specifically the 2019 film Godzilla: King of the Monsters. She has elements of both human and Titan, making her very difficult to mistake for ordinary. Golden eyes, long dark hair a tail, claws, and, depending on her state of mind and emotional state, Dorsal plates are easy enough to spot on a supermodel figure.
After the Battle of Boston, Monarch managed to recover genetic material from Godzilla, and began running tests on it. The loss of Dr. Serizawa was a severe blow to the organization, but not a crippling one. Monarch as a whole rededicated itself to learning more about the Titans. Experimentation with Godzilla's genetic material led to the discovery of Godzilla's extreme adaptability. This led to the questions of to see what would happen when Godzilla's cells were combined with human stem cells taken from multiple sources were conducted. The hope was that Godzilla's regenerative abilities could be reverse engineered and used to bring about the discovery of cures for diseases currently considered incurable. What they got however, was something utterly unexpected. An all new life from that was a combination of the best elements of both human and Titan was born from the addition of Godzilla's DNA to the human stem cell collection.
Aware of the Japanese word 'Kaiju', which meant 'strange' or alternatively 'giant' beast, this new Titan was named Kaijin, taken from the Japanese word intended for human sized, but no less strange, creatures once they were aware of what was gestating in their culture tubes. Despite having been created unintentionally, Monarch refused to terminate her, simply because she could represent a new evolutionary leap forward for humanity. Classified as Titanus Gojiran due to her combined traits and her close relation to Titanus Gojira (aka Godzilla), Kajin grew from embryonic state to infant quicker than anyone could anticipate. While her aging slowed once she reached the physical age of a one year old infant, there was a worry that she might be more beast than girl. These fears were unfounded, as her behavior was a mixture of both species, and she quickly proved adaptive and intelligent. Armed with bleeding edge technology, Monarch educated her in a VR environment. By the time she was twelve, she had absorbed the basics needed to survive among normal people when it came to basic scholastic knowledge due to her soaking up everything they taught her like a sponge. Though she was by no means a genius, her thirst for context to the world around her made her eager to learn, at least for a little while.
But no child can be contained forever, much less one with the abilities and powers she displayed. And Kaijin was anxious to meet other people, as she knew there were more out there. As puberty hit, she became more and more rebellious about wanting to leave Monarch's aegis. Once she realized she could breathe underwater and survive at incredible depths, it didn't take her long to escape from Castle Bravo, Monarch's underwater fortress headquarters, and make her way to America, where Monarch caught up with her shortly after making landfall. Exposed to the world— which was sharply divided on how to handle her— Kaijin was naturalized as an American citizen, taking up residence in New York City, where Monarch set up a special residental embassy as well as a research center where she could interact with other humans, allowing her the chance to live in the world around her and still be able to study her. The compromise, for the time being, was more than enough to satisfy the youn Titan.
Kaijin is relatively friendly, as long as you're not an adversary. She's curious about the world. She's been 'taught' via a form of virtual reality while she was gestating. But just because she 'knows' something in the abstract doesn't mean she's really experienced it, and there's a lot her education didn't cover since she wasn't really expected to just go out and co-mingle with people. So as long as you're not trying to hurt her or people she likes? She's perfectly friendly. She's not as gullible as some might think however. Her creators didn't go to all that trouble just to raise a fool, after all.