Like many fans, Tso has a huge collection of memorabilia and more than 30 CDs and records by his idol. He has attended almost all of Tsui's concerts since she made a comeback two years ago, even following her to Malaysia and Macau. The tickets and travel cost him more than HK$20,000.

'I waited for her backstage every night after the performance,' he says. 'I wouldn't be able to live with myself if I didn't do it.'

Tso insists he's nothing like the desperate autograph-seeking teenagers highlighted by the media. 'I outgrew that. Now we just talk as equals. What I like about her [Tsui] is how she treats her fans. She's very gracious and addresses everyone's requests.'

For the past three years, he's also been hosting a weekly podcast on a website dedicated to the veteran singer (paulatsui.com). 'I feel it's my mission to bring her music to as many people as possible. I'm proud of what I did ... she changed my life,' he says.

Tso surrounds himself with reminders of Tsui in such everyday items as ring-tones and wallpaper, but insists 'I'm only interested in her career'. Some fanatical fans won't brook any criticism or jokes about the star, but 'that's way too extreme' he says. His family accepts his fixation too. 'I'm a great fan, but I know it's only for leisure.'

Although the pursuit of stars is often linked to giddy teenagers, Victor Wong Cheong-wing, a

social work professor at Baptist University, says the association is unfair. 'There are many adult fans, but we don't know them because it's not reported.'

Whatever their age, fans derive more from their passion if they understand their motivation, Wong says. 'Some people are motivated to learn if they are really into something - an Ayumi Hamasaki fan may be more driven to learn Japanese than the average person. So it's important to recognise what you like about [the stars] and see if you can learn from them. Turn idols into role models,' he says.

It may be difficult to look beyond the public persona that music companies allow fans to see. Still, 'there's something to learn from everyone', Wong says.

'In the end it's about what you are looking for yourself.'

Virginia Cheng Tse-wai is drawn to her idol's strength of character. She has been a fan of singer Shirley Kwan Suk-yee since the mid-90s. One of the few Canto-pop stars to embrace alternative music, Kwan mixes different ethnic influences and genres, and Cheng says she is captivated by the singer's haunting vocals, versatility and passion for innovation. 'She is the only local Canto-pop artist I listen to now,' says the product-development professional.

Like Tsui, Kwan recently returned to the stage after a break of more than 10 years and her concerts were emotional affairs for fans such as Cheng. 'She was simply superb - the songs, the dancing, everything,' she says. 'It was perfect. It's the first time I saw her live and it's my dream come true.'

Having grown up in Canada, Cheng says the east-west influences in Kwan's music help her overcome her sense of homesickness in Hong Kong. 'Her music gives me the strength to move forward when I feel tired and uncertain,' she says.

More than that, the singer's 'courage to battle the odds encourages me to meet challenges even when things are not going my way', Cheng says. 'I have always admired her dedication to creating distinctive music irrespective of whether it's going to make the karaoke charts or not.'

Lee Sing, a professor of psychiatry at the Chinese University, suggests few local fans will go to the extremes seen with Yang. 'Hong Kong people are generally more pragmatic. I don't see them giving up everything to pursue idols.'

That's especially true of adults who have family responsibilities, work and other social relationships, unlike teenagers who are still searching for an identity, Lee says. 'They project themselves onto the idols and identify with them.'

Despite their image as teen idols, pop duo Twins have more to offer fans than just good looks. 'I love their stamina,' says Joe Hsieh

Yuet-ngor, a leader of the Twins fan club. 'When they set out to do something, they always persevere to the end. That's why their star has shone for years.'

The 29-year-old recreation officer runs the club with Fire Fung Hok-man, a 21-year-old warehouse assistant, and both have spent more than HK$10,000 on Twins memorabilia, including posters, figurines, albums and T-shirts.

But they've passed the phase of adolescent worship, and no longer wait for hours to get autographs and have curbed their collecting sprees. 'I used to skimp on food and clothes to save enough to buy Twins stuff and every magazine that featured them, but not anymore,' Fung says. They've also learn to respect their idols' privacy. 'They're like my sisters now. I think communicating by letter is enough. You have to give them space.'

But like other hardcore fans, they still faithfully attend every concert, paying more than HK$20,000 to support the duo when they toured the mainland, Malaysia and Australia.

Pursuing stars is undoubtedly costly and time-consuming. However, Hsieh and Fung say they pick up valuable skills along the way. 'I've met many different people and seen places that I wouldn't have if it wasn't for this opportunity [to oversee the club],' says Fung.

'Dealing with fans is a formidable job,' says Hsieh. 'They have different demands and personalities and my experience with them has improved my ability to interact with others.'

Both say the Twins' striving for self-improvement pushes them to do the same. 'Look how far they have come,' says Hsieh, who was inspired to take courses in shipping and English. 'Critics said they couldn't hold a note when they started out. Now they can sing live and try their hand at songwriting.'