Yasuko met and married Hiroshi Sato, and in 152 AG she gave birth to their daughter, Asami. Six years later, the Agni Kai Triad raided the Sato estate and Yasuko lost her life during the break in at the hands of one of the members.
Yasuko's death became the primary factor in manifesting Hiroshi's deep hatred toward all benders, eventually causing him to join the Equalists to avenge her death.
Yasuko shares a similar past to that of Kya, the mother of Katara and Sokka. Both women were killed by firebenders that entered their homes, albeit for different reasons, when their children were very young, and the death of each woman caused their respective spouse to take action: Hiroshi joined Amon and Hakoda led the Southern Water Tribe to fight in the Hundred Year War.