It is the first campaign for the brand from Portas since it was appointed to the account in February.
The spot will launch the brand’s new position, "Be you", which Gary Kibble, marketing director for Sainsbury’s Argos, said was based on "some rich customer insights that gives permission for the brand to be more active, empowering and inspiring."
Sainsbury's Argos is the unit of the Sainsbury's business incorporating its non-food brands, including Tu, Argos and Sainsbury's Home.
The creative director for the campaign was Zara Ineson. It was directed by Finn McGough through Knucklehead, and the media agency is PHD.
The ad is notable for featuring street cast people, rather than fashion models, who appear in familiar surroundings. Kibble called the campaign a "bold new step" for Tu.
"The brand has always followed the codes of high street clothing retailers with traditional fashion shoots," he said.
"We wanted to break those conventions and show that normal people look equally fashionable in our clothing as models. It’s all about personal choice and confidence and less about slavishly following the trend.
"The campaign is emotive, relatable and feel-good. It’s the opposite of a traditional, highly-polished fashion ad."
The brand was striving for a "bright, adventurous, upbeat and naturally stylish" image, he added.
The campaign is set to run until 4 December and will also include out of home, print, digital, in-store communications, content and social media.
Richard Danks, brand director at Portas, called Tu a "sleeping giant".
"It's the sixth largest clothing retailer in the UK with collections that are as good as the best high street fashion retailers," he said, "but it's not thought of as a destination." The long-term goal, he added, was to create "a standalone brand and destination that just happens to be stocked in Sainsbury's."
The campaign, Danks said, was a response to fashion advertising that too often feels old school, indistinct and just not that relevant for everyday people."
Any similarities with the Sainsbury's Food "Food dancing" campaign, created by Wieden & Kennedy, were coincidental and not a strategic decision, he added.
"The work you see today was developed in the pitch process, which took place before "Food dancing" launched. So we weren't aware of the great work on "Living well" at all. That said, it's interesting that we both landed on the importance of casting real people, showing diversity and creating an emotionally upbeat handwriting."