Dear King of Medicine (2020)

Both are lighter historical dramas in which the FL ends up in another girl's body, living that girl's life, and still sees her in dreams/illusions for much of the series.

Both are lighter historical dramas with a similar tone and pacing. The FL ends up in another girl's body and lives her life, and the ML is ill or cursed and initially stand-offish/cold.

Both MLs are healers with a divine past and a cold personality and the FLs are herb fairies with a cheerful and endearing personality.

Both have a similar first half where a plant fairy, who does not understand what love is, makes a high ranked deity fall in love with herself. After that both series get more serious, but Ashes of Love gets a hundred times more serious and angst heavy, while Dear Herbal Lord stays quite light all the way through.

They both try to get the attention of the male leads. In dear herbal lord, she tries to marry the herbal lord, and in a female student arrives at the imperial college, she tries to get the attention of the main male lead. Love both actors and actressess.

Both are fantasy/historical dramas with a similar vibe/feel. The FLs are cute and endearing, as well as non-human, and the MLs are in a position of power and initially seem cold.

Both are historical dramas in which the FL is in another's girl's body.
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Both are historical/fantasy low budget dramas that are mostly light and fluffy. Both FLs are plant fairies, both MLs suffer from an illness and seem sort of cold/aloof.

A naive girl from another world chases the cold guy and makes him totally in love with herself. Both are super funny and have lots of kisses, especially Dear Herbal Lord has many good kiss scenes.

Both are fluffy fantasy dramas with an endearing and innocent plant fairy FL and an immortal ML. Both dramas have a very similar tone and feel.

Both are historical fantasies with a light, fluffy tone and a sweet romance. Both FLs have two distinct personalities inhabiting the same body.

Both dramas have a FL whose soul is sharing the body of another girl, with the two switching personalities.