A Star-Bulletin source said that Nagasako's name will come before the school board this evening for confirmation.
The 46-year-old principal of Nanakuli High School, is also president of the Oahu Interscholastic Association, another post he will have to resign.
He will assume his new duties in July.
As president of the HHSAA, Nagasako has overseen the transition of the association from an agency tied to the Department of Education to an autonomus organization.
The HHSAA officially became independent on July 1, 1995, the day Nagasako become president.
During his term as president of the OIA, the league football playoffs expanded from an eight- to a 12-team format and the consolation playoffs were eliminated.
The league also decided to move the semifinals and finals of the girls' basketball playoffs into Blaisdell Arena.
Leilehua High School principal Norman Minehira, the OIA vice president, is expected to succeed Nagasako as president of the league.
Minehira and other members of the HHSAA executive board will be candidates to succeed Nagasako as president of the HHSAA.
The other executive board members - all principals - are Baldwin's Wallace Fujii, Waiakea's Dan Sakai, Kamehameha's Anthony Ramos and Kauai's Linda Tanoue.
Minehira also is expected to be a candidate for president of the HHSAA.
The new HHSAA president will be chosen by the executive board.
Nagasako has been the Nanakuli principal for the past six years. He was vice principal at Waipahu for two years.
Kaimuki athletic director Dwight Toyama will become executive director on July 1 when Ed Kiyuna ends his 17-year tenure in the HHSAA post.