Fortysix will be a standalone agency within the group with digital creative clients. It will be led by Lewie Allen, who De Groose calls a "digital native" and help clients reach the "ad-blocking generation".
He does not have an advertising background but De Groose explained Allen has the digital creative skills that the industry is looking for, and can work at pace.
There will also be an advisory board with people in and outside the industry.
The agency will by staffed from people outside the industry, and De Groose aims to have around ten members by the end of the year. She said they will also be "digital natives" and people who can "work and operate in a different way".
In an interview with Campaign, De Groose explained that hiring people from disadvantaged backgrounds to join current agencies has not worked because they feel different to their colleagues and do not fit in.
De Groose explained that, instead of bringing them into a shop and telling them what to do, Dentsu Aegis Network is asking them to build an agency and effectively tell the network how to do things in the new world.
To launch Fortysix, the company worked with Freeformers, which helps businesses in digital transformations, to employ staff including Allen.
De Groose said: "The time has come to be brave and look at doing something different and many of our clients are looking for something different. The old world is not delivering everything they need.
"They are looking for new forms of creativity that solves business problems, and they’re looking for that at speed. They’re looking for it from an understanding from the digital natives and the ad-blocking generation.
"Everyone using this agency will get different diverse solutions quicker from a generation who understands ad-blocking the most.
"When clients use this they will also be doing good because we will be bringing people from disadvantaged backgrounds and training them up. They will be investing in a career for people who wouldn’t normally get a break and get the opportunity to come into our industry."
The name of the agency reflects the average number of human chromosomes and shows the "people-centred spirit of the agency".
De Groose said the agency began planning Fortysix 46 days ago, hence its name.