Snow White with the Red Hair, Vol. 24 (manga)

A romantic retelling of a classic fairy tale about a beautiful herbalist and a lovestruck prince. Shirayuki is an herbalist famous for her naturally bright-red hair, and the prince of Tanbarun wants her all to himself! The prince from the neighboring kingdom, Zen, rescues her from her plight, and thus begins their love story. Obi and Eisetsu are undercover at a masked ball, but they're not acting like themselves! Most of the other partygoers also seem a bit off, except for one noblewoman.

With her wits still about her, the woman flees from the venue-and Eisetsu follows in pursuit!