[1] He attended Boston University, where he received his Bachelor of Arts degree in comparative political economics.

He continued analyzing federal research and development budgets under the Trump administration, expressing concerns around flat or decreasing investments in science, particularly around addressing climate change and environmental protections.

[7][8][9] In the winter of 2020, Koizumi worked on the Biden–Harris presidential transition, leading the National Science Foundation Agency Review team.

On January 15, 2021, Koizumi was announced as the chief of staff for the Office of Science and Technology Policy.

[1] Koizumi is also a competitive athlete, winning a gold medal in the 40 to 44 age group for the 110-meter hurdles at the 2010 Gay Games in Cologne.