Onece group was a group of five BFF-1 bulk freighters operated by the Mugaari in the Javin sector.
Following the Battle of Hoth one of the freighters, Onece 3, was recruited as a transport for Rebel Alliance escapees trying to sneak through Imperial lines.
However, while passing through the Imperial checkpoint at Outpost D-34, a TIE/LN starfighter piloted by Maarek Stele scanned the vessels for illicit cargo and discovered the hidden Rebels. With the aid of Stele in lowering the freighter's shields, Delta-class DX-9 stormtrooper transport Sigma disabled the offending craft with ion cannons, then boarded and captured the fugitives despite the arrival of several Alliance Lambda-class shuttles to defend the ship.
Once the hostile craft were all either destroyed or driven off, the captured freighter of Onece group departed into hyperspace, bound for an Imperial impound yard.