[6] Hosoda briefly served as Acting LDP Secretary-General following Sadakazu Tanigaki's hospitalization for a spinal cord injury in July 2016.

[11][12] Hosoda was a member of the LDP Parliamentary Group on the Promotion and Conservation of Japanese Sword and Ironwork Culture, which supported subsidies for Tatara steel.

[14] After he was twice hospitalized over the summer months in 2023, Hosoda stepped down as the Lower House Speaker due to health problems.

[16] On 10 November 2023, Hosoda died of multiple organ failure at the hospital in Tokyo, at the age of 79, just one month after he resigned from the House of Representatives.

[17] After stepping down as chairman, Hosoda was reportedly hospitalized and absent from plenary sessions, but says that his condition suddenly deteriorated the day before his death.