Lala's younger twin sisters, Momo and Nana Deviluke, have settled into Rito Yuuki's school and his home, and Momo has quietly fallen for him. Unwilling to take him from her sister, she sets out to gather a harem around Rito instead, betting that if he marries Lala and becomes king of Deviluke he can marry every girl who loves him, herself included. This sequel to To Love Ru also pushes the alien assassin Golden Darkness, known as Yami, toward the center of the story.