The manga centers on Emma, the daughter of the wealthy owner of the global-scale Howard Real Estate company. She possesses particular powers that her father has used in his business. When the American company expands to Japan, Emma takes it as an opportunity to go to a Japanese high school. She seeks to make contact with a certain assassin family named Tsukishima, and to this end she enrolls in the same school as Ren Tsukishima, a member of the family.