[2][3] A native of Tokyo, he graduated from Keio University with the bachelor's degree in Political Science in March 1997.

After retiring from that in March 2003, he started managing real estate in order to earn studying in the United States and caring for his father.

In June 2005, he received a master's degree in Public Policy from John F. Kennedy School of Government at Harvard University in the United States.

[citation needed] He is married to Tamayo Marukawa (a member of the House of Councillors and former announcer of TV Asahi).

[citation needed] Otsuka received an estimated 8,740,000 yen in unreported income from Seiwakai (Abe) faction fundraising parties between 2018 and 2022 related to the 2023–2024 Japanese slush fund scandal.