Reishin Hong serves as Minister of Civil Administration, commanding the department charged with bureaucratic appointments and administration. He belongs to the prestigious Hong clan, Saiunkoku's second-highest noble family. Within the clan, he occupies the position of middle son between eldest brother Shouka Hong and youngest brother Kurou Hong. Though Kurou publicly acts as clan head after Shouka's departure from the main estate, Reishin wields significant authority and influence over clan affairs behind the scenes.

Academically distinguished, Reishin achieved the second-highest rank ("Bougen") in the Imperial Examinations during his youth. He maintains a close professional and personal friendship with the enigmatic Chief Minister of the Treasury, Ko Kijin, and crafts decorative masks for him despite Kijin's notoriously unsettling appearance without them. He also shares a longstanding friendship with Tei Yuushun, who ranked first in their examination cohort. Reishin masters the biwa, a traditional Hong clan instrument.

Reishin adopted Kouyuu Ri after rescuing him from dire circumstances. Kouyuu had endured a traumatic childhood involving abandonment, slavery, and being left as a sacrificial offering. As Kouyuu's adoptive father and bureaucratic superior, Reishin exhibits a complex dynamic of care and distance. He supports Kouyuu's career advancement yet struggles to express his feelings directly, leading to misunderstandings. Kouyuu deeply admires Reishin but harbors frustration over his perceived emotional detachment. Reishin is married to Princess Yuri, a half-sister of the former Emperor Senka. She provides stability and practical guidance within their household, positively influencing Kouyuu's upbringing.

Reishin harbors intense, often obsessive protectiveness toward his niece, Shuurei Hong, daughter of his elder brother Shouka. He goes to great lengths to conceal their familial relationship, fearing Shuurei might resent him for effectively replacing her father as clan heir. He secretly sponsors her application to take the Imperial Examinations (barred to women), resulting in accusations of manipulation that lead to his house arrest. This triggers a clan-wide work stoppage protesting his innocence. He reacts with extreme hostility toward potential suitors for Shuurei, even expressing a wish to marry her himself until Shouka reminds him of his existing marriage. Figures like Ko Kijin exploit this obsession to provoke reactions from him.

Reishin possesses hidden knowledge regarding his family's secrets. He is aware that his brother Shouka is "The Black Wolf," a legendary assassin who served the previous Emperor. He deliberately conceals this truth from their younger brother Kurou. He also knows the true identity of Seiran Shi, the adopted retainer in Shouka's household, recognizing him as the exiled Prince Seien. Reishin acts to shield Shouka and Seiran due to this knowledge.

Later events reveal Reishin's hidden past and motivations to Shuurei during her investigations related to Kouyuu's imprisonment on corruption charges. Consequently, Reishin is removed from his position as Minister of Civil Administration. Following this dismissal, he departs the capital and returns to the Hong clan's home province, marking a significant shift in his political life and relationship with Shuurei.