Seiga Riku

Seiga Riku is the undersecretary of Censorate, known as the "Official Killer" for his ruthless persecution of officials. He first appears during Shuurei and Suou's investigation of counterfeit currency and artwork, posing as an official looking for a position in order to join Shuurei and Suou's investigation. In truth, he was actually sent to monitor and report on Shūrei's actions.

Seiga is an ambitious and cynical man who does not think highly of Shuurei, particularly because of her idealistic outlook towards working for the government, and he often harasses her.

A promising and confident official, he is known for his willingness to sacrifice others to achieve his goals, much to Shuurei's displeasure. However, Shuurei looks to him as a senior during her time as a censorate official and regards him as a rival in hopes of winning his approval through her own efforts, a relationship that Seiga reluctantly reciprocates.

(Source: Wikipedia)