Born and raised in Hachiōji, Hagiuda graduated from Waseda Jitsugyo High School, and Meiji University with a Bachelor of Commerce degree in 1987.

An anonymous source claimed in a tabloid that Hagiuda had made regular visits to the Church in Hachioji during his time out of office from 2009 to 2012 and was "like one of the family."

[4] When Kishida reshuffled the cabinet and party leadership in August 2022, Hagiuda was appointed Chairman of the Policy Research Council for the LDP.

[5] In December 2023, he resigned as Chairman of the Policy Research Council amid a financial scandal involving the Liberal Democratic Party.

His personal website also lists "trying new restaurants" as a hobby, calling him a "self-proclaimed gourmet", and also mentions his frequent enjoyment of after-meal ramen.