Hayashi served as a member of the California Board of Registered Nursing and as Chair of the Planned Parenthood Golden Gate Political Action Committee.

She is a former board member of Girls Inc of Alameda County, and served as the honorary chair for their "Strong, Smart and Bold" annual luncheon.

[citation needed] Hayashi's journey from her childhood in Korea to prominence as a health care leader is documented in her book, Far from Home: Shattering the Myth of the Model Minority.

She has also championed public education, authoring AB 142[9] to help increase funding for schools through changes to the California State Lottery.

In late October 2011, Hayashi was charged with theft after being caught shoplifting $2,445 worth of merchandise from San Francisco's Neiman Marcus store.

[12] Hayashi subsequently pleaded no contest to a charge of misdemeanor grand theft, and was sentenced to a $180 fine and three years' probation.