Ireland captain Rhys Ruddock is joined in the back row by Dan Leavy and Jack Conan as Roux and Devin Toner are paired in the second row with Cian Healy, Niall Scannell and John Ryan filling the front row positions.
Luke McGrath makes his first start for Ireland at scrum-half and his half-back partner is Paddy Jackson. Rory Scannell starts at inside centre alongside Garry Ringrose in midfield and there is an all Munster back three combination with Simon Zebo at full back and Keith Earls and Andrew Conway named on the wings.
There are two uncapped players among the replacements – Kieran Treadwell and Rory O'Loughlin alongside James Tracy, Dave Kilcoyne, Bealham, Jack O'Donoghue, Marmion and O'Halloran.
The match kicks off at 14:00 local time (06:00 Irish time) and is being broadcast by Eir in ROI.
IRELAND v Japan – Ecopa Stadium, Shizuoka, Japan
15. Simon Zebo (Cork Constitution/Munster) 34 caps
14. Andrew Conway (Garryowen/Munster) 1 cap
13. Garry Ringrose (UCD/Leinster) 9 caps
12. Rory Scannell (Dolphin/Munster) 1 cap
11. Keith Earls (Young Munster/Munster) 60 caps
10. Paddy Jackson (Dungannon/Ulster) 23 caps
9. Luke McGrath (UCD/Leinster) 3 caps
1. Cian Healy (Clontarf/Leinster) 68 caps
2. Niall Scannell (Dolphin/Munster) 5 caps
3. John Ryan (Cork Constitution/Munster) 7 caps
4. Quinn Roux (Galwegians/Connacht) 2 caps
5. Devin Toner (Lansdowne/Leinster) 48 caps
6. Rhys Ruddock (c) (St Mary's College/Leinster) 14 caps
7. Dan Leavy (UCD/Leinster) 3 caps
8. Jack Conan (Old Belvedere/Leinster) 2 caps
16. James Tracy (UCD/Leinster) 2 caps
17. Dave Kilcoyne (UL Bohemians/Munster) 18 caps
18. Finlay Bealham (Buccaneers/Connacht) 6 caps
19. Kieran Treadwell (Ballymena/Ulster) Uncapped
20. Jack O'Donoghue (UL Bohemians/Munster) 1 cap
21. Kieran Marmion (Corinthians/Connacht) 14 caps
22. Rory O'Loughlin (Old Belvedere/Leinster) Uncapped
23. Tiernan O'Halloran (Buccaneers/Connacht) 4 caps