|“||Deep within it, the Abyss creeps into your mind. Eventually, it'll get your body as well. Unlike the curse from the 6th Layer, those don't manifest immediately. For every expedition, you'll stand at the precipice of death and insanity, twisting the skin off your head.||”|
—Ozen, to Lyza asking her about what was up with her hair, Chapter 16
Ozen "The Immovable" (オーゼン) is a legendary white whistle delver who has made outstanding discoveries of the Abyss and retrieved numerous artifacts of incredible value. Even among her fellow white whistles, Ozen is renowned for her incredible physical strength. She is a mysterious entity, shrouded by countless rumors that are absurd but hard to refute.
Ozen is an exceedingly tall and rather slim woman that stands at over 2 meters of height. She has a strangely shaped monochrome hairstyle that is styled in a special way to conceal the scalp deformations caused by the extended exposure to the Curse of the Abyss.
Her eyes are pitch black and lusterless, giving her a rather unsettling and disturbing gaze. When fully equipped for delving, she wears bulky armor and a disc-shaped hat that covers her eyes.
Her White Whistle is adorned with a pair of horns, giving it a bovine appearance. Despite being more than half a century old, she appears quite youthful, with the only thing showing her age being her white hair.
A coldness dominates her personality, and she can often be cruel, cynical and apathetic; even after discovering that she couldn't even scratch Reg during their fight, she continued to hit him anyways, citing that 'after a while [she] just got too into it'. She despises lying to children, and rarely lies to them — even if it means telling them brutal truths. Ozen has absolute control over her facial expressions and as a result her actual feelings (or lack thereof) cannot be guessed with any certainty.
However, she is not completely devoid of warmth and it is shown that secretly she dearly cares for Lyza. When Riko and Reg departed from the Seeker Camp to delve further into the depths of the Abyss, Ozen revealed that she would've liked it if she didn't need to send them off before she could reminisce more about Lyza. She also treated her newest apprentice Maruruk for the most part kindly, treating him well and allowing him to stay at the Seeker Camp so that his eyes could be spared of the surface's light.
Despite her youthful appearance, Ozen has been a White Whistle for over 50 years. Some time in her life, she came to know a young Lyza. Initially unwelcoming of Lyza, she attempted to drive the young girl off by the threat of violence. It was only through Lyza's stubbornness and refusal to leave Ozen alone that Ozen was convinced of allowing the young girl to become her apprentice. The two became very close with each other, and within time Lyza became a fellow White Whistle. They were mutually fond of each other; upon finding Ozen with injuries on her hand, Lyza vowed to annihilate whoever gave her the injury.
She was one of the members of the expedition to descend to the 4th Layer in search of the artifact, the Unheard Bell, along with Lyza and her husband Torka. Though she is deeply fond of Lyza, her love stopped there; when Lyza introduced her to Torka and declared that they were married, Ozen appeared dismayed and unaccepting of the decision. As they made their journey down to the Fourth Layer, Ozen and her comrades fell to tragedies; many died, including Lyza's husband Torka. When she reached the Fourth Layer and found the Unheard Bell, the numbers in their party had dwindled significantly; she and Lyza were one of the few who had survived the descent.
Sometime after the discovery of the Unheard Bell, Ozen was forced to help Lyza give birth; sadly, Lyza's child was stillborn. On a whim, Ozen took the child's corpse and placed it inside the Curse-Warding Box. Weakened by the birth and grieving for her child, Lyza asked Ozen to give her some time alone, leading to Ozen vacating the shelter they had.
Cursing Torka for getting Lyza pregnant then dying and leaving Lyza alone, Ozen began to make plans for her ascension, deciding that her best route would be to take the bell and Lyza while leaving the Curse-Warding Box where it was. It is then that she noticed the cries coming from within the box, coming from the resurrected Riko. At the behest of Lyza, Ozen abandoned the Unheard Bell and helped to carry the Curse-Warding Box to the 2nd layer. Several times Ozen contemplated abandoning Riko and the Curse-Warding Box, but she persevered regardless, in a duty to Lyza.
Two years later after Riko's birth and just before Lyza's "Last Dive" into the depths of the Abyss, Ozen had her last conversation with Lyza while viewing Orth from a balcony. She commented on the disturbing actions made by Riko when coming out of the Curse-Warding Box; the moment she was released, she tried to crawl towards the center of the Abyss. It is then that Ozen promised Lyza that, when the time came, she would reveal to Riko the truth of her nature. Some point in time, she became the guardian of the Seeker Camp, also becoming the mentor of Maruruk and the commander of the delving team "The Layabouts".
When Riko and Reg came to the Seeker Camp, she commanded her apprentice Maruruk to lower the camp's gondola down so that the two could rise. Recognizing Riko immediately, Ozen led them inside. Seating the pair down in a sitting area of the Seeker Camp, Riko gave Ozen her mother's White Whistle so that she could examine it. Ozen was surprised to see the whistle, as she thought that she'd never see the whistle ever again. Right after, Riko thanked her, for lending her help in carrying Riko back to the surface after her birth. Hearing that, Ozen coldly admitted that she often pondered ditching her and leaving her body behind during the ascension to the surface. Reminiscing about the Unheard Bell excursion further, Ozen began muttering cryptically.
After being brought back to her senses by Maruruk, Ozen inquired to Riko, wondering why how she arrived at the Seeker Camp, given her status as a Red Whistle; Red Whistle delvers are prohibited from descending more than 400 meters. Aside from rules dictating that Red Whistles cannot venture further the 1st layer, the difficulty of the 2nd Layer also acts as a deterrent for inexperienced Red Whistles — the harsh environment of the 2nd Layer is too difficult to bear.
Interested in finding out how two Red Whistles arrived to the Seeker Camp of their own merit, Ozen instructed Maruruk to lend an ear to Riko and Reg in her stead; her reasoning was that it would be easier for children to talk to children. At Ozen's instructions, Maruruk gave the two Blue Whistles; Ozen noted that it would be troublesome to explain the presence of two Red Whistles in the Seeker Camp, so for the time being they would wear Blue Whistles. In exchange for the Blue Whistles, she took Lyza's White Whistle as collateral insurance, and she told them that they could exchange the Blue Whistles for the White Whistle when they were about to leave. After explaining, Ozen requested that Reg and Riko stay overnight, telling Riko to take a bath because she smelled of vomit.
The next morning, following Riko wetting Reg's bed, Ozen walked into Riko explaining to Maruruk and Reg what caused her to lose control of her bladder — a strange monster. Ozen then noted mysteriously that Riko's ignorance was not due to herself, but due to negligence by Habolg and Jiruo.
Bidding Riko to follow her if she wished to know the answers to her questions, Ozen began to walk up the stairs inside of the Seeker Camp. During their ascension of the stairs she told Riko several things; Ozen told her that the letter supposedly sent by her mother was fake, that her mother was dead and buried in a grave in the 4th layer, and that she happened to have found the letter and the whistle on that grave. When Riko expressed disbelief at the revelation, Ozen retorted; the handwriting on the letter wasn't Lyza's. Furthermore her mother wouldn't have ever written such a message, not even as a joke.
Soon Ozen brought Riko and Reg to her chamber, where she showed them a white cube. Immediately, Riko noted that the design present on the cube was incredibly complex, suggesting that it was an artifact above 2nd grade. When Riko questioned why the cube wasn't in the artifact catalogue, Ozen explained that it had been bought by Lyza before being auctioned off, and hence wouldn't be found in the artifact catalogue. Riko then guessed that it was the Curse-Warding Box, to which Ozen admitted that she was half-right.
Ozen revealed the true nature of the box; although the box is reputed to protect those contained within, truthfully it does not. Things within the box would still be affected by the Curse of the Abyss, and would still die. However, instead of remaining dead, things within the box will begin to move.
Without pause, Ozen gave Riko a chilling truth; the only reason that she knows the effect of the box is because it was demonstrated to her through Riko; she was born stillborn and when Ozen placed her corpse into the box, she came back to life. The monster that Riko had saw the night before had been created by Ozen, when she had been reminded of the box's power and tried placing some meat she had for a meal into the box.
The monster that she had created the night before ceased moving after some time had passed, and Ozen disposed of it promptly. She revealed an observation she had made between Riko and the monster she created; both were trying to reach the bottom of the Abyss.
She is a peerless fighter. About 120 Thousand-Men Pins have been embedded in her body, and grant her superhuman strength, speed, and vitality. However, she can't put a scratch on Reg using her relic.
- Apparently, she likes odd-tasting food.
- "Do you have a conception of God? The people around here, you see, don't believe in God. Do you know what is it they believe in? The answer is this place - the Abyss itself." (To Reg)
- "Don't stay in the deep layers if you don't want to kill those who are waiting for you." (To Riko & Reg)