[39] On January 15, 2021, Ilgan Sports identified Rowoon as the male lead,[11] but FNC Entertainment stated that for the moment he was focusing on filming She Would Never Know and nothing had been decided.

[40] In the following months, Nam Yoon-su,[13] Choi Byung-chan[15] and Jung Chae-yeon[41] joined the cast; meanwhile Park Eun-bin and Rowoon were confirmed on March 19, 2021.

[42] Nam decided to participate in the series to gain new experiences and because he had found the character of Lee Hyun unpredictable,[43] while Rowoon because of the love story told and because he wanted to try his hand in a historical drama.

[55] Filming locations also include Hangae Village in Seongju County and Hanjujeongsa Temple on its summit;[56][57] Gyeonggijeon Temple, its hyanggyo (provincial school) and hanok village in Jeonju,[58] Munheon Confucian school in Seocheon County,[59] Mungyeong Saejae provincial park in Mungyeong,[60] Buan Cinema Theme Park,[61] Itaesarang rock in Geochang,[61] Manhyujeong pavilion in Andong,[61] Gwanghalluwon garden in Namwon,[62] and two fortresses, namely Jukjusanseong in Anseong and Sangdangsanseong in Cheongju.

Several outlets felt that it opened a new horizon in the stories of women disguised as men, and that Hwi's independence and how she repeatedly saved Ji-woon constituted a 180° shift in the gender roles of a typical romantic series,[37][76][77] appreciating "the rare attempt" to make the female lead occupy a higher social position, instead of recounting the sad love between a high-ranking man and a woman of humble origins,[38] and observing that the concept of the woman who pretends to be a man transcends the dimension of melodrama, extending towards the dimension of battles for values and self-affirmation, and comparing it to the struggles against prejudice fought by minorities excluded for their diversity.

[79] AlloCiné found that the intonation is evocative of Mulan, but observed that the series stood out for its very light plot, and narrated the sentimental wanderings of a young woman in a fundamentally patriarchal environment, calling it "feminist in more than one way".

[38][78] Compliments were also directed to the aesthetics of the sets and costumes, and to the interpretations of the protagonists,[80] especially to the performances of Choi Myung-bin in the roles of both Dam-yi and her brother Hwi as children,[81] and to the more nuanced one by Park Eun-bin,[76][82][83][84] whose complete identification with the character was considered one of the main reasons for the popularity of the series.

[38][77] Moreover, the drama attracted positive comments for the portrayal of youth fighting against the status quo in order to protect their rights and happiness, freely expressing, in an imaginary world, metaphors of reality and social taboos that are difficult to manage in a series set in modern times,[37] for example the older generation's attempt to arbitrarily define and classify young people according to its own desires:[78] in particular, Han Ki-jae's ambition to wield power by maneuvering Hwi like a puppet evoked the election campaign for the new President of South Korea and the way in which the political community incited young people to vote.

[38] Popular culture critic Jung Deok-hyun noted, however, that while it might have been possible for a crown prince to fall in love with a eunuch, seeing Ji-woon courting Hwi was disconcerting, as, taking into account Joseon's power structure and discrimination between men and women at the time, it would have been more common to witness the opposite, considering Hwi's position of greater power; consequently, he found the dynamics between the two characters implausible, also due to the fact that Ji-woon ignored Hwi's true gender, and observed that, if the relationship had been treated with greater seriousness and foresight, it could have become a true queer drama, especially if the production decided to opt for the story of a true homosexual love.

[38][85] On the other side, Tae Yoo-na of Hankyung found the development sloppy, characters awkward, and casting wrong, arguing that Park Eun-bin's physique and height were too small compared to Rowoon's, preventing her from expressing the dignity of a crown prince.