One popular 'human to monster transformation' light novel is 'Overlord'. In it, the main character Momonga is trapped in a virtual game world and gradually transforms in a sense into a more monstrous and powerful being as he rules over his new domain. He has to deal with various races and challenges in the game world which he now dominates.
Another is 'Tensei Shitara Slime Datta Ken'. The protagonist Satoru Mikami is reincarnated as a slime, which is a form of monster transformation. He starts from being a weak slime but through his unique abilities like 'Predator', he absorbs other beings and their powers, growing stronger and evolving into a more complex and powerful monster - like entity. He also builds his own nation of monsters.
Identity crisis. The transformation makes the character question who they are. Are they still the same person inside? In 'Overlord', Momonga has to deal with his new identity as a powerful being in a game world and how that differs from his human self. He has to adapt to the moral and ethical implications of his new form and power.
In human into monster transformation stories, a prevalent theme is the power that comes with the transformation. Some stories show how the character gains superhuman strength or abilities as a monster but at the cost of their normal life. Another theme is the fear of the unknown. The transformation is something that is not understood by the character or those around them, leading to a sense of mystery and horror. Also, there's the theme of transformation as a form of evolution, where the character is evolving into a different form, whether it's for better or worse.
One popular example is 'Beauty and the Beast' - like stories where a female human and a monster - like character fall in love. Another could be 'A Shade of Vampire' series which has elements of such romances. There are also some indie light novels available on platforms like Wattpad that might explore this genre.
There's 'Beauty and the Beast' in a way. The prince is transformed into a beast as a punishment. It shows his inner state of being cold - hearted before. Also, the 'Ancient Greek myth of Lycaon' where Lycaon is turned into a wolf. It was a story of divine punishment for his impiety. These stories all explore different aspects of human into monster transformation.
One common theme is the idea of acceptance. The female human has to accept the monster's different appearance and nature. For example, if it's a werewolf, she has to accept his wild side. Another theme is the power of love to bridge the gap between two very different beings. Love is shown as something that can overcome the fear and prejudice that might exist towards the monster.
There were a few light novels with the main character being a monster emissary that could be recommended. The first one was "Monster Breeder from the Other World ~ Cultivating with a Plug-in ~", which told the story of the protagonist's experience of cultivating monsters in the other world. There was also "The World's Only Monster Envoy ~ Mistaken as the Demon King after Class Advancement ~", which revolved around the adventure of the protagonist being mistaken for the Demon King. In addition, there was also "The Weakest Monster Envoy Begins a Trash Picking Journey", which described the adventure of the Weakest Monster Envoy. These light novels all used the monster as the main character, bringing the readers a fantasy adventure story.
Typically, they start with the encounter. The human girl stumbles upon the monster, either by accident or some fated event. Then there's a period of fear or mistrust from the girl's side, as she tries to understand the monster. As time passes, she begins to see the good in him. For example, he might save her life or show her kindness. This leads to a growing bond, and eventually, they fall in love and face obstacles together, like society not accepting their relationship or other threats.
😋I recommend the following two novels to you: " Heavy Armor of Hurricane " was a sci-fi novel that traveled through time and space. The protagonist could travel through different time and space and achieve different effects by transforming. " My Body Has a Divine Beast." This was a futuristic novel. The main character merged with a Divine Beast in an accident and possessed the power and abilities of the Divine Beast. From then on, they began a thrilling journey. I hope I can satisfy your needs. If you like it, feel free to tell me anytime.😗
In 'Shiver', the main plot revolves around a girl named Grace who has always been fascinated by the wolves in the woods. One of the wolves, Sam, is actually a werewolf. Their relationship develops as Sam is about to lose his humanity. It's a story of love against the odds of his changing nature.
One of the main themes is power dynamics. With monster lords being powerful entities, the novels often explore how they interact with each other and those with less power. Another theme could be loyalty, as the characters, whether they are monster lords or those associated with them, often have to decide who to be loyal to in different situations.