Momo, and it's empty.

Momo Yaoyarozu was enjoying a simple stroll along the beach, admiring how close it was to being completely pristine. "I wonder who has been cleaning this up?" she mused. "We definitely need more people willing to do these small things for the community." She stretched as she enjoyed the evening sun. It was only a week left until the applicants would be taking U.A's entrance exams. Recommendation Students like herself would be taking their own entrance exams for it, so she has been studying hard. But even with her intellect and diligence, she needed a break.

Her toe impacted something, making her yelp and jump back. "Ow!" she groaned. "...it seems whoever is cleaning up missed a bit of debris here..." She looked down, and blinked as she saw a golden, Arabian style lamp. "...well, this is quite a find," she mused, picking it up curiously. She wondered how much it was worth. Not that she needed the money, given her background, but it looked and felt like solid gold. She began brushing sand off. Suddenly, glittering red mist erupted from the spout, and enveloped Momo.

"What the!?" she demanded, trying to get out of it, but found that she couldn't move. She tried not to panic, assessing her situation. Was this some kind of esoteric Quirk? She attempted to use her own to make a fan to blow the mist away, but nothing happened. Then, to her alarm, she saw her one piece swimsuit was dissolving into the mist.

Left naked, she renewed her struggles, but made no headway. Then, her body felt overcome with some sort of pleasant sensation. A tingling as the mist seemed to be absorbing into her body. All of her hair that grew below the neck fell out, and she felt her breasts grow more sensitive, and slightly in size. She moaned, it felt good, but she still was afraid of what was happening. The mist then started forming new clothing around her. She blushed heavily as what seemed to be a translucent red Middle Eastern harem outfit materialized on her body, fitting snugly, and made of some luxurious silk. Despite the embarrassment she felt at the get up, she couldn't deny it was amazingly comfortable.

The mist started to recede as the tingling sensation intensified in her feet and legs, and she looked down and shrieked as she saw her toes were dissolving into the mist, which remained connected to the spout of the lamp. She began thrashing to try to pull away, but she was firmly connected to the mist as the effect traveled up her feet, then her legs. It finally ended as her thighs and hips were consumed, leaving her floating off the ground, her lower half now a tail made of the mist. The tip of said tail was attached to the spout of the lamp. She found she could move it, the motions coming naturally, like it had always been a part of her body. She tried to pull it away from the lamp, but it wouldn't detach. Nor would the lamp budge as she attempted to pull it. It was like for her, the lamp was Thor's hammer, and she was unworthy.

She then felt another surge of alarm as she felt an inexorable pull on the tail, drawing her into the lamp. "No, no, someone help!" she cried out, trying to move away, but her efforts failed to even slow herself being drawn in. With an audible pop, she entered the lamp.

...

Blinking, Momo regained her bearings, finding herself in a lavish room. Even the accomodations at her own home seemed to pale in comparison to the sheer luxury currently around her. Was she really inside the lamp now? Before she could question it further, she felt her mind becoming pleasantly foggy. "Oh..." she moaned as she put a hand to her head, but felt disinclined to fight the sensation as information flowed smoothly into her mind, which expanded in order to accommodate it all.

After a minute, she had full understanding of her situation. She was a genie now. Specifically, a genie specializing in sexual wishes. She blinked as she processed this all, and how her very soul had changed. She placed a hand on her chin as she pondered these revelations.