Uhhh unless I previously misunderstood that myth, you're kind of leaving out the part where the reason she wanted to have a man's body was because she had been raped. By Neptune.
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After raping her he offered her anything she wanted, and she asked to be turned into a man so that she could become invincible and not be forced to bear anyone's child.
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She didn't outright ask for impenetrable skin, but it was hardly out of the blue.
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This is literally the story of a woman who was so tormented by people lusting after her and being raped that she felt the only recourse to solve the issue would be to live in a man's body.
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After raping her he offered her anything she wanted, and she asked to be turned into a man so that she could become invincible and not be forced to bear anyone's child.
.
She didn't outright ask for impenetrable skin, but it was hardly out of the blue.
.
This is literally the story of a woman who was so tormented by people lusting after her and being raped that she felt the only recourse to solve the issue would be to live in a man's body.