Spears Funabashi Tokyo Bay advanced to the Japan Rugby League One final following a 24-18 win over Tokyo Sungoliath in a tough, physical encounter at Prince Chichibu Memorial Rugby Ground on Sunday that had more than its fair share of drama.

A red card in the fifth minute, two disallowed tries late in the second half and a lengthy referral to the Television Match Official five minutes after the final hooter all went against Sungoliath and ensured it was the Spears that advanced to next Saturday's final against reigning champions Saitama Wild Knights at National Stadium.

"It was a crazy game, so many things happened," said Spears coach Frans Ludeke. "But our leadership group kept the team together and stayed on task and ground it out. In the big moments when we had to score, we stayed together as a team and turned pressure into points."

"It's our first-ever final and we have worked hard to deserve that opportunity."

Tries by Malcolm Marx and Bernard Foley in the 56th and 77th minutes looked to have sealed the win for the Spears, who played most of the game with a one-man advantage following a red card to Sungoliath lock Hendrik Tui in just the fifth minute.

But Sungoliath had other ideas.

Aaron Cruden brought the teams to within six points with a try in the 80th minute before Taiga Ozaki looked to have given the former All Black a chance to win the game with a conversion after he crossed two minutes into time added on.

However, the TMO, for the second time in the space of 20 minutes, disallowed Ozaki's "score" due to an earlier offense.

With the crowd of 13,065 on the edge of their seats, there was still time for one more twist as the Sungoliath pack continued to defy their numerical disadvantage and their driving maul crossed the line.

But following a lengthy discussion between all the officials, it was deemed the ball had not been touched down, handing the win to the Spears.

"We will enjoy the victory and then start preparing for the final," said Marx.