The Ikale Tahi Rugby side held their first training session at the Kochi Stadium in Japan, Wednesday.
The team was welcomed in a traditional Japanese manner in Kochi on Monday night.
Tonga will be facing England in their first match of the World Cup.
The team is under the guidance of Toutai Kefu, who was born in Tonga but made 60 caps for Australia during his playing career. He took charge of the Tongan national team shortly following the 2015 World Cup. Their most recent result was a crushing 92-7 defeat to New Zealand.
The historical record for this match is one-sided, with England having won both of their previous games against the Tongans. England's largest scoreline against them was 101-10 in October 1999.
Tonga qualified for the RWC through their second place finish behind Fiji in the Pacific Tri-Nations. They come into the competition with momentum after defeating the Fijians in June and beating the French Barbarians more recently after consecutive defeats to Wales and Georgia.
Their squad includes the likes of scrum-half Sonatane Takulua and star full-back Telusa Veainu.
Tonga will play against England in their first game of the 2019 Rugby World Cup on Sunday, 22 September 2019.
You can watch the game live on Digicel Play TV and stream live on the PlayGo app.