Glasgow forwards Ryan Wilson and Jonny Gray are the only forwards to remain in the pack, which features six more changes from the Georgia win. Allan Dell, captain McInally and Willem Nel form the front row.
Edinburgh lock Grant Gilchrist returns to partner the reinstated Gray in the second row, while the capital club's Hamish Watson and John Barclay join Wilson in the loose forwards.
"We've had a really productive week's preparation in Nagasaki ahead of our arrival in Tokyo, with our players adapting to the time zone and weather conditions out here in Japan," Townsend said.
"As we've got closer to the game our training has been more about fine-tuning the hard work that's gone in over pre-season into a focus for Sunday's game.
"Our team has a lot of experience playing together in major games for Scotland, with a bench capable of making a difference when required. That cohesion, experience and leadership is very valuable in a build-up to a match of this magnitude as well as during the 80 minutes on Sunday.
"In Ireland we face a quality opposition who, over the past number of years, have earned the right to be the number one ranked side in the world.
"We know them well and are well aware of the strengths they possess throughout their squad. We expect them to play very well, as they did in their most recent games against Wales, so only our best performance will do in order to win.
"The prospect of facing them in the opening round of a Rugby World Cup is a fantastic challenge for our players and supporters around the world."
15 Stuart Hogg (Exeter Chiefs)
1 Allan Dell (London Irish)
2 Stuart McInally CAPTAIN (Edinburgh)
3 Willem Nel (Edinburgh)
4 Grant Gilchrist (Edinburgh)
5 Jonny Gray (Glasgow Warriors)
6 John Barclay VICE CAPTAIN (Edinburgh)
7 Hamish Watson (Edinburgh)
8 Ryan Wilson (Glasgow Warriors)
16 Fraser Brown (Glasgow Warriors)
17 Gordon Reid (Ayrshire Bulls)
18 Simon Berghan (Edinburgh)
19 Scott Cummings (Glasgow Warriors)
20 Blade Thomson (Scarlets)
21 Ali Price (Glasgow Warriors)
22 Chris Harris (Gloucester)
23 Darcy Graham (Edinburgh)