Chief Cabinet Secretary Yasuo Fukuda on Tuesday will tie the record as the longest-serving official to work as a prime minister's right-hand man.
On Wednesday, he will break the record of Shigeru Hori, who held the post for 1,258 days while working for the Cabinets of the late Prime Ministers Shigeru Yoshida and Eisaku Sato.
Fukuda, 67, was appointed to the position in December 2000 by then Prime Minister Yoshiro Mori, succeeding Hidenao Nakagawa, who stepped down amid a scandal involving his alleged relationship with a woman suspected of using illegal drugs.