Both are historical dramas of a shorter length in which the leads are working together to solve strange mysteries.

Both are historical mini dramas in which the leads are working together to solve mysteries.
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Both are mini dramas in which the leads are working together to solve strange mysteries, and one of the two is secretly working for someone else and may end up on the opposite side of the other lead.

Both are mini dramas in which the leads are working together to solve strange mysteries.
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Both are mini dramas in which the leads are working together to solve strange mysteries and uncover a secret.

Both are mini dramas about a strange mystery that the leads are working together to solve. Both MLs have a hidden identity, and both FLs are hiding a secret.

Both are mini dramas with a similar dynamic between the leads who are trying to solve a series of mysteries.

In both dramas, the FL approaches and stays close to the ML because he has or she believes he has the heart of someone close to her (brother vs. first love).

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Both are mini dramas in which a married couple are driven apart due to scheming relatives. Years later, the FL returns, bringing with her a child/children the ML never knew existed.

Both are about a couple who are driven apart by scheming and evil relatives. Years later, the FL returns, bringing with her a child/children the ML never knew existed.

Both are about a misunderstanding or lies that drive a couple apart. Years later, the FL returns with a child/children the ML didn't know existed, and the two become close again.