Whanganui, West Coast and Horowhenua Kapiti will each celebrate a centurion, with Horowhenua Kapiti marking two on the same day.
Whanganui's Dane Whale will become the union's 15th centurion, a decade on from his debut against South Canterbury in August 2014.
The Taihape product has spent most of his career steering the team from first-five, and it's a role that has suited him: he kicked the winning drop goal in the 2017 Meads Cup final and captained the side through 2022 and 2023.
Rugby runs deep in the Whale family. His father Kerry was a Whanganui centurion himself, playing between 1985 and 1998, and Dane has shared a jersey at different times with both his brothers, Ben and Luke, though never all three together.
Whale Senior will present his jersey at Saturday's pre-match meal, with a framed jersey and a blazer marking his 100th game to follow.
In Gisborne, West Coast's Sean McClure reaches his century in an away fixture. The Hokitika electrician made his debut in 2011 and has spent 15 years covering almost every position in the backline, a versatility that has made him one of the most adaptable players the union has produced.
He becomes West Coast's third centurion. Because the game is away, the celebration will be shared with his teammates on the day, before a formal presentation is held for family and supporters when the team returns home next week.
Those close to the union describe him as a quiet, understated leader, more comfortable letting his consistency speak for him than any fuss made in his honour.
Horowhenua Kapiti will mark two centuries in the same match, as David McErlean and Aaron Lahmert both reach 100 games together.
McErlean, a Foxton dairy farmer, becomes the union's ninth centurion in its 133-year history. A dynamic front-rower who can cover tighthead, loosehead and hooker, he has played in two Ranfurly Shield challenges and three finals, including a try that won the 2018 Lochore Cup.
Lahmert, a Waikanae mechanic, becomes the union's 10th. He has represented the NZ Heartland XV three times, turned out for the Hurricanes Development side against Japan A in 2018, and received his 25th HKRFU blazer alongside his brother Warwick.
Both men were shown video messages from teammates at Thursday's training, before their whānau join the squad for a pregame jersey presentation and a centurion cap presentation at the after-match function.
Three unions, four milestones, and one shared thread: the dedication that defines Heartland rugby. Whale, McClure, McErlean and Lahmert will each pull on the jersey for the 100th time this weekend, a reminder of the passion that keeps this competition thriving.