The defending champions first won the title in 2011 before winning it again last year.
Vaiala is in Pool A, alongside Satalo, Moatoa and Ulutogia.
The host team, Marist St Josephs is also the favourite of the competition after winning the title 12 times.
Marist is in Pool D alongside Lupesiliva, Faleolo Jets and Malie Sharks.
Auckland Marist St Josephs and Fiji’s Tabadamu are the only overseas teams that have won the title.
Auckland Marist won it three times while Tabadamu only won it in 2019.
The Vailima Marist 7s tournament will be held on Friday and Saturday at Apia Park.