Two further wickets fell before stumps as Otago's bowlers earned three bonus points, but the opening day was still Munro's, who will have designs on adding to his one test cap.
Elsewhere, a century from another batsman on the fringes of the New Zealand set-up saw Northern Districts take a similarly commanding position against Canterbury in Gisborne.
Daniel Flynn's 16th first-class ton saw ND recover from the loss of Brad Wilson in the opening over and helped validate his own decision to bat at Harry Barker Reserve.
Flynn put on 144 with Joe Carter (64) for the second wicket before Andrew Ellis (4-70) tore through the hosts' middle order and left them in the unconvincing position of 228-6.
But Bharat Popli and Mitchell Santner - a pair with fewer than 10 games' first-class experience between them - combined to advance their side to 341-6 at stumps, with both men making unbeaten half centuries.
ND, stuck at the bottom of the table, will be desperate to win against first-placed Canterbury, with defeat opening an almost insurmountable deficit.
Meanwhile, the wickets continued to fall at McLean Park in Napier, the scene of last week's three-day win for Central Districts. The hosts again used the conditions to their advantage against Wellington yesterday, rolling the second-placed visitors for 172 in 51 overs after they elected to bat first.
A first-wicket stand of 68 between Josh Brodie (51) and Michael Papps (45) was as good as it got for Wellington. In reply, CD reached 103-5 at stumps.