[ All lore in Onmyoji is released through a combination of events, "memory scrolls" and videos. SOURCES: 1, 2, 3, 4, 567, 8, 9, 10, 11 & 12. ]
Prior to becoming "Suzuka Gozen", she was called Rei. As one of the two daughters of the queen of the Eternal Sea, she was the child born with the power to control the tides and was thus known as the one who would inherit the queenship in the future, serving her homeland as the protector and guardian of the Eternal Sea. Her older sister, Sen, did not possess the power of the (merdragon) bloodline, although she desperately wanted to protect the Eternal Sea as well. Raised by their mother to successfully inherit the power of the tides, Suzuka Gozen met an ill fate in the midst of the ascension rite - while she successfully took on the mantle of protector, as well as the power of the tides, a cataclysm struck and she went missing from the Eternal Sea. The cause of the cataclysm was unknown, but it cost the realm of the Eternal Sea their power, their protector and their security as the Sea was plagued by a steadily-encroaching ice that would threaten to freeze solid the entirety of the Sea one day. Her mother and sister, left behind, would do all that they could could stave off their demise.
Rei, without memory or name, found herself on distant and unknown shores. As a nameless mermaid of great power, she came to dominate over a tribe of demons in the area she had awoken in. Despite her lack of memory, she was a formidable and well-organized leader, and her exploits and tactics caught the attention of the local daimyo. Under the daimyo's command was a general called Tamura and his daughter, Youko. Displeased by Tamura's allowance for Youko to learn the ways of bushido, as well as his popularity among the soldiers, the daimyo sent the two of them with a meager retinue to subjugate the demon presence on an island near the sea. The battle was, as expected, an overwhelming loss for the humans; with their medical unit eviscerated by the demons and Youko, one of the premiere swordmasters, fatally injured, they were forced to retreat - thus, abandoning Youko. At the ships, Tamura's prayer for Youko's return ( although unlikely, due to her injuries ) was met with the sight of his daughter walking out of the mists, the head of a demon in her hand, proclaiming to have killed the leader of the demons. Relieved that she had made it, Tamura embraced his daughter and the two of them returned home to recover from their injuries and announce their success.
Based on her achievements during the battle, Youko was awarded the title of "Suzuka Gozen" and the two were heralded by the local population as great heroes. Youko was well-loved by the people in response, living among them with a broad smile and easygoing charm, likened to a soldier that one could be easy friends and easily loyal to. A rumor eventually sprung up, that despite her feats and her sense of justice, she had "the temper of a demon" and a casual thief was nearly killed by her, only prevented by the timely approach of a fishmonger who offered her a fine tuna if she would only let the man go. While the people grew apprehensive, a representative of the local fishermen came to petition to the daimyo for aid in dispatching a powerful demon who had begun to harass the fishermen. Youko was dispatched by the daimyo, and at the coastline, she met a young Otakemaru - no more than a child. He proved a match for her, though she fought like a woman with one hand tied behind her back - as though afraid to truly unleash her might. Backed into a corner by Otakemaru, her father called out to her: I do not mind if you use your true power. No matter what you are, I believe in you. His encouragement, and his permission, allowed her to shed her human guise and battle Otakemaru in her true form -- that of the nameless mermaid that formerly lead the demons of the island.
After defeating Otakemaru, she approached Tamura, who admitted that he had known all along -- his daughter had perished, and the woman before him was not her. Despite his grief, he asked her for the truth of what had happened to his daughter -- and the nameless mermaid, Suzuka Gozen, told him. The two of them had fought; Youko, fatally wounded and indomitable, had been relieved to hear that her people had retreated, despite that it meant leaving her to her death. The mermaid, in her confusion, demanded to know how Youko could be so calm, so happy about being abandoned, to which Youko responded that it was because those people were her family, and her family was her strength. Not understanding the concept of 'family', the mermaid asked Youko to explain what she meant. As Youko agreed to, she was struck from behind by another demon and perished immediately. Donning her form, the mermaid slew that demon, and came to present its head as the "head of the demon leader" to Tamura, seeking to find the meaning of family among the humans and the man who embraced her immediately that day. Expecting him to be angry or disgusted, that she had impersonated his daughter, she was shocked to see him come to her defense as the daimyo's men stepped up to capture the two of them as conspirators against him. Her, for being a demon and Tamura, for harboring her knowledgably. Tamura, announcing that "his daughter" had done no wrong, was last seen facing the daimyo's men down as Otakemaru took Suzuka Gozen's hand and they fled to the sea.
At sea, the two of them returned to the island that Youko had perished on, and began to transform it into a place they could call home. Changing it from a battlefield to an island inhabited by demons who simply wanted to live freely, away from the humans that would not understand them, Suzuka Gozen became the leader of the Mt. Suzuka demon band, with Otakemaru growing as her right hand and younger brother. The demons were her family, and she guarded them zealously for years and years. After Mt. Suzuka was established, she began to have reoccurring nightmares of Tamura and the fate of his soul; the dreams finally forced her hand, and she left Mt. Suzuka to Otakemaru and her generals and went in search of Higanbana, a spirit of the underworld who could lead her to the place where Tamura's soul was trapped, suffering. She dealt with the problem, freeing the man she called 'father' from his torment, and left the underworld in only three days -- to find that, in the mortal realm, it had been two hundred years since she had vanished. In her absence, Mt. Suzuka had been hit by a blight and Otakemaru had lead the people of the newly minted 'Sealand' to war with Kyoto, seeking to dominant the land in order to revitalize Mt. Suzuka. Otakemaru's onslaught had failed, and he had died.
Confused and furious, Suzuka Gozen attended the Night Parade of the Hundred Demons (Demoniac Feast) to both take responsibility for what her people had done in her absence, as well as to demand answers about the two hundred years of events she had missed. Aoandon, the great spirit of stories and tales, was able to fill her in on Otakemaru's actions and the corruption that had suddenly plagued Mt. Suzuka, forcing their people to starve and scrape for sustenance until they had been lead on a war campaign for their very survival. Unable to find his soul during her search for answers, she decided that - before she would attend her task, bequeathed upon her by the onmoyji Abe-no-Seimei, she would return to Mt. Suzuka and find out what had happened to it while she was gone, and she would find Otakemaru, her most important person. With her went the onmyoji Yao Bikuni, a woman who had become immortal after eating the flesh of a mermaid. At Mt. Suzuka, the two of them worked alongside the key generals of Sealand's army to determine why Mt. Suzuka had become corrupted. The work of a cabal of miasmatic imps, slowly desecrating the island's sacred trees and memories had caused the corruption, and during the investigation, the imps attempted to consume the remains of Otakemaru's soul -- which was still protecting his home all that time -- and break the boundary of Mt. Suzuka in order to infest the world. Suzuka Gozen and her entourage battled and defeated the imps, culminating with Suzuka Gozen binding half of her life with Otakemaru to ensure the two of them are never parted again.
After handling Mt. Suzuka, she attends to her task: purifying a shard of Ungaikyo, the Demon Mirror, at the Eternal Sea. Her arrival at the frozen Eternal Sea is, unbeknowst to her, the first time she has returned to her birthplace in over two hundred years. There, she is tasked by the queen to assist the remaining mermaids in unthawing the Eternal Sea, spurning Sen, the elder daughter who had been working tirelessly for centuries to perform the task her sister, Rei, was given the right to do. Suzuka Gozen seizes the Shell Staff, an artifact of great power and uses it to bind the tides to her might, proving herself as the long-missing Rei in the process, which crushes Sen. After bringing the tides to heel, Suzuka Gozen approaches the queen, who betrays her and attempts to take the power of the tides and the royal power that the queen had bestowed upon her daughter all those years ago. The queen is exposed as an imposter: the real queen had been attacked when weak by the male mermaid that she had coupled with and was meant to consume, leaving the male mermaid adopting the form of the queen as he plotted to take over the power of the seas. Too debilitated to fight him, Suzuka Gozen is forced to watch Sen fight and defeat the former King, then use the power of the Shell Staff to unthaw the seas. The act took Sen's life in the process, and once more left Suzuka Gozen unable to protect her family.
BACKGROUND.