Abs are so last century.

In Taiwan at the moment, the craze is for oblique muscles, or a well-defined V line that dips way below the waist, as popularised by President Ma Ying-jeou’s son-in-law, former model Allen Tsai Pei-jan.

Making a V line: Male celebs and their merman lines
From left: Jay Chou, Song Seung Heon and Aaron Kwok

Mr Tsai’s marriage to Mr Ma’s daughter Wei-chung, 33, was reported last month and the 33-year- old finance executive’s modelling past was quickly brought to the fore. So was his V line, which is so pronounced and eye-popping in photographs of him in low-rise jeans, it might well be a 3-D visual effect.

Also known as renyuxian or merman line in Mandarin, the look is a new must-have for male stars from Taiwan.

Actor-singer Vanness Wu (pictured above) wore his like a badge of success for his appearance last week on the Chinese celebrity diving show Stars In Danger.

Making a V line: Male celebs and their merman lines
Vanness Wu at Stars In Danger. Photo: China Foto Press

He made quite a splash in the media on both sides of the Taiwan Strait, and veteran singer Bao Xiao-bo, who will appear on the programme later this month, has been training hard for his chest, abs and obliques to look as good. “I’m the old version of Vanness,” Bao, 45, told China Times.

Through the lens of the oblique-obsessed Taiwanese media now, there appears to be only haves and have-nots.

Wu, 34, has an Apollo’s belt, as the look is also known classically. So do – or did – stars such as singer Jay Chou, 34, and actor Eddie Peng, 31.

Actor Wu Chun, 33, who owns a gym chain, is believed to have a V line, but he refused to flaunt it in public in Taipei last week. Instead, he told his fans: “You are all so lecherous.”

Farther afield, in Hong Kong, singer Aaron Kwok, 47, is the undisputed merman king.

In South Korea, home to the gym-toned likes of actor Song Seung Heon, 36, and Super Junior singer Choi Si Won, 27, the look is practically a uniform.

Making a V line: Male celebs and their merman lines
Choi Si Won. Photo: SM Entertainment

V lines are not forever, however.

Chou, who unveiled his obliques in publicity pictures for his album Opus 12 late last year, admitted last month that his V line had grown “fuzzy” after his Chinese New Year eating binge. Later, he said: “Now everyone is revealing it, so I won’t.”

This article was first run in The Straits Times newspaper on April 14, 2013. For similar stories, go tosph.straitstimes.com/premium/singapore. You will not be able to access the Premium section of The Straits Times website unless you are already a subscriber.