Ririnui is well known in Rotorua as a quality goalkicker and kicked five out of five for Whaka yesterday, after kicking six from six last weekend in Opotiki.
The big first five was described by his coach after the game as "safe", relieving pressure time and time again with his long, clearing kicks.
Whaka coach Ngarimu Simpkins said it was a good win against a tough opponent.
"We knew they were going to be tough. I have never played in an easy Whaka-versus-Rangataua match," he said.
"They are a tough Maori side and you always know these games are going to come right down to the end."
He said his team showed plenty of maturity not to concede when put under pressure yesterday.
"They showed a lot of character," he said.
"It showed the maturity of some of these players, not cracking under pressure.
"This was another game where we were put under pressure but we believed in our systems and held on."
Simpkins said they were building a strong culture in the club this year with five straight wins. Whaka will face their toughest test of the season on Monday when they travel to Tauranga to play defending champions Tauranga Sports.
Yesterday's match did not get off to a good start for Whaka after one of their reserves was stung by a bee in the warm-up and had to go to hospital, suffering an allergic reaction.
Rangataua scored the first try of the game after forcing a turnover and spreading the ball wide.
Outstanding winger Siaosi Iongi was involved in the move which ended with Alex Jessop crossing in the corner.
Ririnui scored Whaka's first try a few minutes later after breaking a few tackles close to the line.
Whaimotu Craft-Chemis linked up with Chanse Perham to score Whaka's second try of the match, with Perham strolling in untouched down the left edge.
A late penalty to Rangataua made it 20-11 at halftime in favour of the home side.
Rangataua were first to score in the second half through fullback Ross Taurima, but Whaka hit back with a try to Daniel Ngawhika.
Rangataua rallied well to kick a penalty then score a 70m try, which was finished off by Taurima.
Rangataua's Daiyu Ishimori missed the conversion which proved to be the difference in the end.
Meanwhile, Rotoiti lost 20-15 to Greerton at Emery Park .
Rotoiti will play away against Opotiki on Monday.
Whakarewarewa 27 (John Ririnui, Chanse Perham, Daniel Ngawhika tries; John Ririnui 3con, 2pen) defeated Rangataua 26 (Ross Taurima 2, Alex Jessop tries; Daiyu Ishimori con, 3pen); Rotoiti 15 (Joshua White, David Fraser tries; Whakataki Cunningham con, pen) lost to Greerton 20.