The 27-year-old, who stands at 6' 4", signed a two-year contract with Northampton Saints shortly before Ireland's tour to the Far East and is itching to prove his worth to the national set-up.
Stand-in coach Niall O'Donovan said of the Dubliner's inclusion in Ireland's midfield: "David did well when he came on for Kevin (Maggs) last weekend, and we felt he deserved a chance to start.
"I think we're looking forward to seeing Dave start and seeing how he does. He's a very promising player."
Quinlan, who earned his first senior cap as a replacement in last weekend's 44-12 first Test win over the Cherry Blossoms, commented: "There were a fair few nerves, to be honest, when I came on for my first cap last week. Obviously you are not even sure whether you are going to get on or not, but as the game progressed it looked more likely.
"Now I can just concentrate on playing rugby and doing my job for the team."
Quinlan's former Leinster colleague Girvan Dempsey, who makes his 60th appearance in an Irish shirt in Tokyo, reckons Ireland need to up the ante.
"The first Test didn't satisfy us. There were a lot of mistakes, turnovers and we offered Japan a good deal of ball to run straight back at us," said the Leinster full-back.
"At stages, we were a bit cautious in our game plan and I think we're hoping to be more open and expansive - move the ball wide and keep it for longer periods on Sunday."