John Kapualani Koko, charismatic bassist of the Mahaka Sons and its predecessor group, the Makaha Sons of Ni‘ihau, died Monday afternoon at Kaiser Permanente Moanalua Medical Center. He was 51.

Koko’s brother, Sons guitarist Jerome Koko, said the family had been hoping he would receive a heart transplant before time ran out.

Members of Hawaii’s entertainment industry spoke almost as one in describing Koko as a man who was cheerful and upbeat despite his failing health.

Koko "had this way of making every day a special occasion. … We would all go home with sore stomach from laughing so much after a ‘hard day at work,’" said music promoter Sharlene Oshiro.

Hawai‘i Academy of Recording Arts board member Keola Donaghy spoke fondly of Koko’s frequent postings on Facebook and his ability to "make you feel like the star. … I saw him do the same thing to everyone, completely sincere with that glowing smile."

Koko’s commitment to acoustic Hawaiian music, and particularly the acoustic stand-up bass, inspired numerous younger musicians. Koko "set the standard for what many Hawaiian bass players of my generation have considered the epitome of traditional Hawaiian bass-playing," said Kale Hannahs, member of two Hoku Award-winning Hawaiian music groups.

"I know that I’m not the only one to say that I practically learned how to play traditional Hawaiian bass from listening to the Makaha Sons. … His solos in ‘Noho Paipai’ from the 1993 ‘Hawaiian Bash’ album were the first bass solos that I actually sat down to try and learn note for note," Hannahs said.

Hawaiian music historian Harry B. Soria Jr., who watched the Makaha Sons of Ni‘ihau "morph" through several configurations, said Koko "brought an uplifting energy and warmth that seemed to expand as the years went by."

Hawaiian radio personality Kimo Kahoano praised his work ethic: "When he had to have surgery to replace his faulty (heart) valve (several years ago) he got right back to work as soon as he could. … We will always remember him in the rhythm of the bass and (vocal) harmony of the Makaha Sons."

Born in St. Francis Hospital in Honolulu, John Koko grew up in Nanakuli. His musical career began at the age of 12 with Na Leo O Nanakuli, a neighborhood quartet; he later performed as the Koko Brothers with his brother Jerome, a founding member of the Makaha Sons of Ni‘ihau.

Jerome Koko had left the Sons in 1978, but the death of another founding member, "Skippy" Kamakawiwo‘ole, in 1982, and the abrupt departure of the group’s bass player, "Cousin Mel" Amina, left the remaining members — Louis "Moon" Kauakahi and Israel Kamakawiwo‘ole — with two holes to fill. Kauakahi asked Jerome Koko to come back for at least one job that he and Kamakawiwo‘ole didn’t want to cancel.

Jerome agreed to help out and brought John with him. The ad hoc quartet was such a hit that the brothers became permanent members.

The quartet — Kauakahi, Kamakawiwo‘ole, Jerome Koko and John Koko — was the last version of the Mahaka Sons of Ni‘ihau. It was also the most popular and critically acclaimed. The Sons won their first Na Hoku Hanohano awards in 1985. The group’s albums won a total of nine Hokus between 1985 and 1993.

When Kamakawiwo‘ole abruptly quit the Sons in 1993, Kauakahi and the Koko brothers continued on as a trio. The Makaha Sons of Ni‘ihau became the Makaha Sons. The trio’s first album won five Hoku awards, including group of the year, in 1995.

The Makaha Sons received Hoku awards for two subsequent releases.

The Makaha Sons of Ni‘ihau/Makaha Sons received a Hawai‘i Academy of Recording Arts Lifetime Achievement Award in 2010 for the group’s collective achievements and contributions to Hawaiian music.

Although music was his passion, Koko also enjoyed playing chess, oil painting, walking on the beach and traveling.

Keith Haugen described Koko as "a wonderful example of how to be upbeat, friendly, involved and not feeling sorry for oneself while suffering with a bad heart condition. … He brought smiles to many, right up to the time he left us."

The Rev. Dennis Kamakahi said succinctly, "The Hawaiian-music world lost a true musical soul."

In addition to his brother, Jerome, John Koko’s survivors include his wife, Toni; his sons, John Jr., Jerman, Jordan and Jerry; and two grandchildren.

Condolences can be sent c/o The Makaha Sons, P.O. Box 1246, Waianae, HI 96792.

Donations to help with his medical expenses can be made to "John Koko — A Heart Gift" at any First Hawaiian Bank branch.

Funeral plans are pending.