For neutral observers the choice of who to support in the Women's World Cup final is an easy one. The two-times World Cup winners USA, the powerhouse of women's football who have appeared in all four Olympic finals? Or Japan, whose journey to a first final has gripped a nation and provided a much-needed source of optimism for a country still grieving following the devastating earthquake and tsunami in March?

In terms of women's football it is David against Goliath, but one where David has an emotional backstory that resonates with anyone with even the smallest hint of compassion.

Along with the golfer Ryo Ishikawa, who has promised to donate all tournament earnings this year to the disaster fund, this Japan side have become global ambassadors for a nation.

All major sporting tournaments tend to be full of empty rhetoric about "winning it for the people back home" or "the pride of playing for your country" but it is no overstatement to say that the Japanese are competing with the events of last March at the forefront of their minds.

Before their quarter-final against the hosts Germany, the Japan coach, Norio Sasaki, showed his squad a slideshow of images of the devastation caused across the country by the tsunami.

They were images the players had all seen before – most had lived through them just four months ago – but the wounds are so raw that to revisit the event led to an instant reaction.

The Nadeshiko – the Japanese for beautiful flower – beat Germany 1-0 in what was the shock result of the tournament. Or at least it was so far.

But emotion is not the only reason the public across Germany have been drawn to Japan. The team have progressed through the tournament playing a brand of high-octane, pressing and passing football that has led Sasaki to grow weary of knocking back questions from reporters desperate to compare his side with Barcelona.

That may seem like a slightly lofty comparison to anyone who has watched a tournament where, at times, the standard of football has been average at best. But with Japan, where the national women's league is semi-professional, the intent to play good football is clearly there, even if they are occasionally hampered by a lack of ability.

The US too have their own dramatic stories which have led to an increasing interest in the country, not least the redemptive journey of goalkeeper Hope Solo, who has become an unlikely hero in a squad packed full of the stars of the women's game.

Solo was sent home from the 2007 World Cup after criticising team-mate Briana Scurry, her rival for the goalkeeping position. Solo had played every game of the tournament until Greg Ryan, the US coach, started with Scurry in the semi-final against Brazil as he felt her added years of experience would be crucial in such a big game.

The plan backfired – the US lost 4-0 – and Solo was sent home before the third-place play-off against Norway for stating that she would have made the saves that Scurry failed to.

The expulsion came not long after the death of Solo's father and one of her close friends and she has spoken of how low she felt following her return home.

She earned her place back to the squad, however, even if the damage never quite healed. "Things will never entirely be the same [with my team-mates]," Solo told Men's Journal. "And that's life."

This tournament has gone a long way towards rectifying that. Solo's penalty save in the quarter-final against Brazil redeemed her in much the same way as Stuart Pearce's penalty against Spain in Euro 96 allowed him to bury his past.

With her good looks, catchy name and Hollywood story, Solo has become a star. The Oklahoma City Thunder player Kevin Durant has promised to name his first child after her; a US marine serving in Afghanistan recorded a YouTube video inviting her to the Austrian Officers Ball; spectators (of both sexes) in the stands in Germany wave marriage proposals scrawled on card and in the space of a week she went from having 10,000 followers on Twitter to over 110,000.

The result on Sunday may be somewhat irrelevant to the success of the tournament as far as the two finalists are concerned.

Once Solo returns from Germany she can expect to become the poster face of women's football in the United States. In Japan the poster contains the coach Sasaki and the 21 women in his squad.