The plot is centered on these twins, Cain and Morana, as the title of the book suggests. Bearing the ancestors' curse, they were born into an unidentified family.
No, it's not that it's unidentified; their family name shouldn't be said casually.
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Name: Cain Suddenly
Age: 5
Gender: Male
Moral: Normal
Self-control: Normal
Habits: always like to ask questions
Talent: Jack of all trades
Greatest fear: Morana Suddenly
Info:
— A very sweet child
— doesn't want to be separated from his twin sister
— Sister complex
— He'll do anything his twin sister asks
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Name: Morana Suddenly
Age: 5
Gender: Female
Moral: Degenerate
Self-control: so-so (If she wants to, she'll do it; no more questions)
Habits: mimicking how the other children act
Talent: Killing
Greatest fear: N/A
Info:
— Aware of Jess existence hidden inside of her twin brother body
— Loves to travel
— She's mute
— Could only talk to Jess