Niamh O’Dowd, Neve Jones and Linda Djougang start in an unchanged front row.
Cliodhna Moloney-MacDonald, the only player in Ireland’s squad with World Cup experience, is the replacement hooker on the bench alongside former England prop Ellena Perry, who made her Ireland debut in the warm-up win over Scotland earlier this month.
Star back row Aoife Wafer – who was named Women’s Six Nations player of the tournament earlier this year – was ruled out by Ireland earlier this week.
Wafer, 22, has remained in Dublin to continue her recovery from knee surgery, but is expected to link up with the squad after the Japan game.
Sunday’s game at Franklin’s Gardens will be Ireland’s first in the World Cup since 2017, having failed to qualify for the 2021 tournament.
Wafer, who will join Harlequins from Leinster after the tournament, scored four tries for Ireland in the Six Nations but missed the last game of the championship after damaging knee ligaments against Wales.
Her fitness has become increasingly significant for Ireland following injuries to fellow back rowers Dorothy Wall and Erin King, who will both miss the World Cup.
Following the Japan game, Ireland face Spain on 31 August and back-to-back world champions New Zealand on 7 September.
“They’re a good team,” Bemand said of Japan, who are ranked six places below Ireland at 11th in the world.
“They’re well-disciplined, well-organised, strong coaching group, so we’re anticipating seeing some stuff we’ve not seen from them before. Pacy, skilful. We’ve picked a team to get our best game out there.”
