The Japan national rugby team returned to Tokyo on Sunday knowing they disappointed a lot of people Saturday in the first of their two games against Ireland.

"Shizuoka turned on a real show for us but we let them down," head coach Jamie Joseph said following the 50-22 loss.

A good crowd of 27,381 -- though like Kumamoto a week before it was probably quite a few more with a number of school children let in for free -- saw Joseph's side handed a lesson in discipline and finishing.

The good news is Japan have a habit of rebounding from poor performances in a two-match series, as they did in 2014 against the Maori All Blacks, losing the first game 61-21 before a last-gasp try saw the Maori win the second game 20-18.

But the bad news is Ireland know that.

"We're very happy with the way we started and Japan probably didn't show how well they can play," said captain Rhys Ruddock. "But they finished strongly and for next week we'll have to be a lot better. We'll have to tighten up our defense and play a bit better kicking game as well."

It was a view backed up by coach Joe Schmidt.

"They will feel they can take us. The speed they moved the ball, the speed of the foot work of some guys, it is not often you see Simon Zebo being taken for speed on the outside but (Kenki) Fukuoka is a sevens player but he isn't bad at this 15s game. He was very sharp. (Kotaro) Matsushima was a handful as well."

The back three of Fukuoka, Matsushima and in particular fullback Ryuji Noguchi was one area Japan didn't let themselves down.

The problem is the talented trio need the ball in their hands to wreak havoc, and it wasn't until the closing stages that Japan were able to do that.

Japan's three wins at Rugby World Cup 2015 were based on a solid set piece. But on Saturday they struggled big time against the Irish.

Solid campaigners like Kensuke Hatakeyama, Luke Thompson and Michael Broadhurst were sorely missed and the scrum was a liability rather than an attacking weapon, with Japan losing as many scrums as they won (three).

First-time tackles were also missed when Japan were forced to defend as Japan seemed to shy away from physical confrontation.

"We need to make our one-on-one tackles, it's international rugby," said a clearly frustrated Joseph.

"But the question we do have to ask is why are we getting into those situations? When you have smaller players tackling bigger players, you need to be a lot more accurate."

The former Japan and New Zealand international also reiterated what he said the previous week about how tough it was for Japan to play any side -- particularly a Tier 1 nation -- when they have men sent to the sin bin.

"We did miss a lot of tackles but a lot of that was when we were down to 14 men. It's very difficult to play against a classy team when you are down to 14 men."

Japan proved under Eddie Jones that they were able to learn for their mistakes and the senior players know they need to do the same with Joseph in charge.

Japan captain Shota Horie -- one of a number of big-name players with a point to prove -- probably summed things up best.

"It's lucky we get to play them again next week," he said.

Lucky, providing the lessons taught have been taken on board.