Five elderly men from Kochi, Japan, with an average age of 68.2 years are taking active ageing to a whole different level - by embarking on second careers as pop idols.

Collectively known as G-POP from Kochi-ke ALL STARS, the 'boyband' came together and released their first single Banzai Old Age in February 2016.

The 'G' is derived from the Japanese word of the same pronunciation, meaning elderly man.

The members are, in order of their age: Iwao Yamamoto, 59, Akira Ohtaka, 66, Yoshinori Deki, 67, Noriyasu Tanioka, 68 and Hidetada Yamada, 81.

Following on the heels of American band Fun's hit song We Are Young, the Japanese heart-throbs released their second single I Was Young last month, featuring choice lyrics such as "When was my first kiss/ when was it/ I totally forgot it/ Oh My God".

The video has garnered 165,000 views on YouTube so far.

Most of the members still hold full-time jobs. Mr Deki has been a fisherman for 34 years, while Mr Ohtaka and Mr Yamamoto are in senior positions in fishing and bamboo processing companies respectively.

Mr Yamada, the oldest, is technically retired but continues to run marathons each year.

Kochi prefecture has one of the highest proportions of elderly people in Japan. The Japan Times reported in 2015 that Kochi's population is expected to decline by more than 200,000 people from current levels by 2040.

The groovy grandpas are not the first geriatric act to make waves from Japan. A 33-woman group from Okinawa, known as KBG84 because of their average age of 84, became so popular that they signed a record deal and toured internationally.

The group performed in Singapore in December last year.