The Butler, Sparring is Chapter 117 of the Kuroshitsuji manga.
Sebastian Michaelis and Elizabeth Midford battle, with the latter determined not to let him pass. Sebastian attempts to persuade her to go home, but Elizabeth refuses to, and he muses that he can "make quick work" of her were she not Ciel Phantomhive's fiancée. He asks her why she does this even though she has always wanted to see Ciel smile, and she asserts that she does not know. In tears, she states that she cannot return. They continue fighting, with Elizabeth shattering the glass window behind Sebastian. In subsequence, Sebastian says that her strength is admirable for a human, and delivers a blow to her chest, which incapacitates her. She tries to stand, but faints instead. Sebastian inspects her and is relieved to find that her bones are not broken, remarking that humans are frailer than he expected.
Sebastian, then, leaves her on the ground with his coat, and enters a facility where blood transfusion experiments have been carried out. He opens a cabinet and discovers bottles of blood sorted by the names of the stars: Polaris, Vega, Canopus, and Sirius; the quantity of Sirius is the lowest compared to the other three. He takes some with him, investigates further, and locate the rooms of those said to be embodiments of the four guardian stars. Said four are not in their respective rooms, however, which prompts Sebastian to contemplate the situation: He can easily destroy Sphere Music Hall and kill Blavat Sky and the others, but that would not be enough to quell the fervor of those who frequent the music hall. He, then, decides to report back to Ciel, and picks up Elizabeth.
Outside Ciel's townhouse, Sebastian corrects the way he is holding Elizabeth, in fear that Ciel will scold him, and then goes in. Ciel and Edward Midford are surprised, with the latter rushing to hug Elizabeth. Elizabeth is transferred to a bedroom, where Edward watches over her. Meanwhile, Sebastian informs Ciel about his entrusting the blood he obtained from the facility to Sieglinde Sullivan and Wolfram Gelzer for Sieglinde to analyze, and adds that he was not able to meet the four with the names of stars. At this juncture, Edward enters the room, questioning why Sebastian came back when he saw proof of the music hall's "evil deeds." Sebastian explains that there is no point in destroying the music hall, as it is merely a symbol, and its ruin can possibly intensify the zeal of the people; crushing the S4 and Blavat, who are "charismatic celebrities" to the populace of London, will only do them harm. Edward asks if there is nothing they can do. Sebastian, sensing Elizabeth fleeing the townhouse, comments on the "irksome" nature of human hearts.