After it was announced that Joseph Manu would be departing the Sydney Roosters at the end of the season to take up an opportunity in rugby union, a former player believes he won't return.

A week after breaking the record for most running metres per game, Manu confirmed that he had signed with Toyota Verblitz, a Japanese rugby union club.

Following in the footsteps of Sonny Bill Williams, Mat Rogers, Lote Tuqiri, and more recently, Marika Koroibete, Suliasi Vunivalu, and teammate Joseph Suaalii, the 2022 Golden Boot winner is just the latest player to make the switch to the 15-man code.

While Andrew Johns always believed that Manu would take a similar route to Sonny Bill Williams', he has predicted that the Roosters centre won't return to the NRL.

"I don't think he will (comeback)," Johns said on Immortal Behaviour.

"I'd imagine that the All Blacks would be watching this really closely. He has a similar skillset to Sonny when Sonny Bill changed over (to rugby union).

"Sonny's skill set changed in the way he played, with the one arm offloads. Joey Manu is that sort of player.

"So I'd say that the All Blacks will be watching closely."

TOPSHOT - Joseph Manu of New Zealand (L) is tackled by Latrell Mitchell of Australia (R) during the Trans Tasman rugby league international between New Zealand and Australia at Mt Smart Stadium in Auckland on October 13, 2018. (Photo by Fiona Goodall / AFP) (Photo credit should read FIONA GOODALL/AFP/Getty Images)

Inking a deal with Japanese rugby, Manu's tenure in the competition would see him play fewer games than he is currently playing.

Instead of normally playing 27 games per season, the games will be minimised to around 16 games and it will last a shorter time-frame.

"He wouldn't train as hard and it's not going to be as taxing on the body," Johns added.

"It's, what, 12 to 14 games a year? He's won premierships. He's won golden boots. He's won best player of the year and best in the world.

"He's going to go and set himself up. He's got a young family and young kids.

"Like any Kiwi boy growing up, the All Blacks is the absolute pinnacle... I'd say that the All Blacks will be watching really closely.

"I wish him well."