Ibara Kuro: Black Label takes place in an alternate version of the 20th century. The steam-powered engine has recently been invented, and the Northern European country Edelweiss is at the forefront of the technological and industrial development. However, a great threat appears: the insane Dr. Theresa Rose has decided that the human race is filthy and needs to be exterminated to make place for a beautiful rose garden, and her very first target is none other than Edelweiss. She and her five daughters (Lace, Shasta, Kasumi, and twin sisters Midi and Meidi) wreak havoc across the country under the name Rose Garden, leaving the Emperor with no choice but to send out his finest: the "negotiators" Bond and Dyne, to defeat the Rose Garden and save the country.