Diarmuid Codyre starts at out-half having led Coláiste Iognáid to the Top Oil Connacht Schools Senior Cup tile on Wednesday,
The game will kick-off at 2pm and Connacht Provincial Talent Coach Colm Tucker takes charge of the hosts.
The starting XV features a number of players that featured in the Top Oil Connacht Schools Senior Cup final earlier this week and is a rare opportunity for the young players to face international opposition.
The Japan team is made up of the best High School players from across the two islands in Japan and this is the second game in their tour of Ireland.
Thomond Park was the venue of their first game as Munster emerged with a 17-7 victory on Wednesday night.
Following Sunday’s clash against Connacht, Japan will go on to face Ulster and Leinster.
Admission to this game is free.
Connacht U19s: Hugh Lane; Michael O’Reilly, Aidi Donovan, Barry Walsh, Graham Kerr; Diarmuid Codyre, Steven Atkinson; Ryan Lomas, Danny Arnold, Mark Keegan; Neal Moylette, Niall Murray; Cian Huxford (C), Dylan Tierney, Adrian Cummins.
Replacements: Ryan Corless, Conall Fallon, Brian Boland, Michael O’Donnell, Pat Howley, Colm Reilly, Michael Hanly, Aaron Martyn, Tom McGann, Cillian McCabe, Tomás Forde.