Nil Admirari no Tenbin EP4 - Nightingale Ball: Nachtigal

As Tsugumi is slowly getting used to her new job with Fukurou, one day, she meets the Prime Minister's son, Ukai Shougo. Having nearly killed himself due to the influence of a cursed tome, Shougo has come to live at Fukurou in order to recover. While Shougo is rude and utterly selfish, Tsugumi finds herself concerned for him. Meanwhile, when a politician jumps to his death due to a cursed tome Fukurou learns that there may be some connection to the dark auctions held behind the scenes of an illustrious dance hall by an organization known as Karasu. Tsugumi accompanies Shougo in an undercover mission to learn more information.