Ok... let's explain this better, you see the reason why there is a True King that's class lower than a queen is because of the mutation that happens within the king. Due to it being able to mutate intelligence it came at the sacrifice of its reproductive system, you see slimes doesn't give birth they divide. King on the other hand being a rare mutation, having its own unique abilities causes it to not be able to reproduce another one of its kind.
The queen on the other hand doesn't have that problem, there was no mutation in its creation other than the fact that it got lucky has a standard normal slime. Esma here only happened to stumble upon an dying deity from the Tetsukuzu region rich in mythical beasts roaming around. I know right mythical beasts in a fantasy world… wow, but unlike other regions this region is known for more intellectual spirits, it has been able to remain mostly hidden from the rest of the continents. Most information from that region Is told by outcast, vagabonds, and ronins that have managed to made it past no man's lands which is a small patch of forest between the Empire and the world. Their stories are always the same that Spirits there are seen as more guardian deities to pray to, and to see at least once in your life. Now back to Esma's story, as a common slime she was just wandering around when she stumbled upon a cave. This cave was known in the region as The Yanagi Cave, it was known to the nearby villages as a deity that did not like to be disturbed, a caring, protective, motherly figure. That brought prosperity and fertility to those who pray to it. Esma first memory recalls her just going into the cave has slimes will normally inhabit dark moist areas to feed off of ore and plants. But there is where she found something much more precious than an ore or plants, staring at her was no other than the guardian spirits Yanagi the three tailed white dog spirit. Lying in a pool of blood, dead from a slash wound running up from her right thigh straight up to her neck.
What had happened was, she was attacked and killed by The 'Arrogant Prince' of the region Tohōmonai Amayakasa Rete Sodatta. They say he first visited her using his authority, to command her to be one of his spiritual concubines. You see in the Tohōmonai Empire the Emperor and his family were already seen as deity. Due to the fact that most of them were born from deities. They were more half spirits than man, this gave them superhuman abilities, as such their appearances is more reminiscent of their bloodline deities as well as incredible magical capabilities. There were some that was more consumed with power than the other one who could not be satisfy their thirst and as such some Emperors and their children would keep concubines up to the dozens, any mythical beast once they had a human-like appearance were fair game. Hence why certain deities were not scene at all, always in hiding, sure they were some who are just too strong to hide and just roamed as they like without being bothered. But then came the prince the fifth born to the emperor, he was not like any of his siblings he had a greed like no other. When accounting his more twisted bloodline magic he had the means to take anything that he wanted, it was said he killed his second older brothers to become third for the throne. But unable to overpowered his second sister and the first oldest sister, he decided to gain more status than them.
The Empire is run by hierarchy, to be in the favor of the current Emperor you have to be loved more by the people, have more successors and just be over all someone that he can leave behind to rule over his kingdom. He knew his sisters had no intention of ruling over the Empire his main target would have to be his eldest brother first in line to the throne. But as kind-hearted, Well spoken, highly intelligent, but oblivious has his elder brother was the Arrogant Prince knew he could not overpower nor outsmarting his brother who was extremely loved by the people due to his bloodline magic one that had came directly from his father the Emperor the Great Mythical Serpent Dragon. But there was one thing he could surpass his brother at to be the successor, you see his brother did not like the idea of concubines and only kept one woman with him and her name was Yanagi.
Unfortunately luck would not have the older brother, for over a half a century she would not have a child. Has the emperor's millennial life was coming to an end, he worried that his fifth son now third in line was close to succeeding to the throne, based on the laws that he had made. But within the blessings of his last breath, he prayed for nothing but prosperity and fertility to Yanagi while holding her hands. This angered the Arrogant Prince to no limits, His veins started to pulse all over his body, Is grinding teeth begin to bare huge fangs, His muscle started to expand more than the skin on his flesh couldn't keep up tearing the flesh off his own body, His bellows of pain could be here all throughout the Empire the dark auburn aura that surrounded him was a mix of his pure hatred and his own blood, his rage burst forth with no restraints his bloodline magic started to show its true colors he was ready to kill everyone near the emperor's deathbed.
His anger was understandable, because he knew the true magic of his father's bloodline magic, the Serpent Dragon was known to be wise powerful and malevolent, but there was one thing that it was known most for he was able to grant any wishes based on its strongest desires. The emperor used his last breaths in hopes for a single successor to be born from his eldest son, he knew that a desire that strong would have prevailed. Unfortunately the sisters knew of this earlier, the plan by the emperor I mean and was able to immediately subdue the prince before you could fully transform they stop him by pinning his hands to the ground with blessed spears, and bond his limbs which chains of unbreakable black steel. They knew they had to keep the eldest brother from showing any form of anger or grief, you see his bloodline magic would not work if you had an ounce of darkness in his heart that's why the emperor used it's only on his last breath. They were able to subdue their brother without their eldest brother every knowing what I had concurred, they quickly transported him to the foot up there great mountain Kenjin. And what seemed like the long awaited blessings from the heavens Yanagi was blessed with a child the following year.