Date of birth: Nov. 24, 1942

Party: DPJ

Electoral district: Lower House; Hokkaido No. 2 (fourth term)

Mitsui, who has served as vice land minister and the DPJ's deputy policy chief, is considered one of the richest members of the party.

Last year, he raked in some ¥50 million in income to place 11th in a list of the wealthiest Diet members, according to data released in July. During his stint at the land ministry, he strongly pushed for the Hokkaido Shinkansen Line, which is currently under construction, to be extended from Hakodate to Sapporo.

He served as health minister in the DPJ's shadow Cabinet during the party's opposition days.

He was elected to the Lower House in 2000.

A certified pharmacist who graduated from Showa Pharmaceutical University in Tokyo in 1966, Mitsui set up a pharmaceutical company and now runs three hospitals and two welfare facilities for the elderly in Hokkaido, according to his website.