Retiring Ireland captain Ciara Griffin was full of emotion after ending her career with two tries and a win over Japan, but insists she is comfortable with the decision she has made.

However, she claimed "now is the right time [to retire] for me and my family".

"That was a lovely way to go out and I will take a lot of solace from that. I want to relish this moment," she said.

Griffin led the team to victory even though they played for 52 minutes in Dublin with just 14 players after Hannah O'Connor's red card.

The captain, a schoolteacher, was in tears during the pre-match national anthems and was also emotional after her starring role on Saturday, with two second-half tries ensuring that Ireland signed off a difficult 2021 with back-to-back autumn wins over the USA and Japan.

"Everyone knows I wear my heart on my sleeve," Griffin said.

"It was the last time signing the anthem for your country and it is an emotional time and something that stands out. It got me.

"The game itself was a mix of everything, wasn't it?

"We acknowledged at half time the things we needed to work on and it was a complete team performance in the second half.

"There is a group of players in there who keep fighting for each other, they don't drop the heads.

"They are very close and have each other's back and when you have that, it's half the battle."

Departing Griffin and Griggs sign off with one last win

Griffin and outgoing head coach Adam Griggs bowed out with one last win - with a squad in transition facing into an uncertain future after failing to qualify for the World Cup.

The team dearly wanted to conclude a difficult few weeks - dogged by off-field controversies - with a home victory in front of their fans at the RDS but they were comprehensively outplayed by the adventurous visitors in the first half.

Yet the incoming coach Greg McWilliams will have been heartened by the battling qualities shown in the second half by a group of players still emerging and learning in the international arena.

Although Enya Breen gave Ireland the lead through a sixth-minute penalty, Japan were the better team in the first half, playing with a high tempo and plenty of accuracy.

That was in contrast to a transitional Ireland side, who conceded eight penalties in the opening half hour and struggled for rhythm and cohesion with so many knock-ons and poor execution.

The Japanese thoroughly deserved their 12-3 interval lead with Mana Furuta capitalising on a fast break by Ria Anoku to score the opening try after 17 minutes.

Ireland suffered a blow when number eight O'Connor received a straight red card for leading with the head on Nijiho Nagata in the 28th minute.

The visitors bossed the closing minutes of the first half with an extra player, and Seina Saito finished off a brilliant team try, with Japan's forwards taking on and beating a physically stronger Irish pack.

Ireland transformed in second half

Whatever was said by Griggs in his final team talk at half-time, or by Griffin, the players certainly responded.

Griffin led by example, charging down Japan's clearance kick for Ireland's first try four minutes after the restart.

Their line-out problems and handling errors of the first half melted away when Griffin crashed over off a pick and go under the posts. Breen's conversion put Ireland 15-12 in front with one quarter of the game still to play.

A bad penalty miss by Breen kept Japan in the game and they had some late pressure, but a huge tackle by Griffin helped Ireland turn the ball over, one final little cameo to give the fans a glimpse of what they will miss in 2022 and beyond.

Ireland: Delany; Doyle; Considine, Naoupu; Sheehan; Breen, Dane; Feely, Jones, Djougang; McDermott, Monaghan; Griffin (captain), McMahon, O'Connor.

Replacements: Moloney, O'Dwyer, Healy, Caplice, O'Leary, Hughes, Touhey, Roberts.

Japan: Anoku; Nagura, Futura, Kobayashi, Imakugi, Otsuka, Tsukui; Kato, Nagata, Lavemai; Tamai, Yoshimura; Saito, Suzuki, Nagai.

Replacements: Komaki, Kokaji, Kitano, Minami, Nagata, Ito, Abe, Yamamoto.

Referee: Clara Munarini (Italy).