The Seattle Mariners announced Monday that catcher Kenji Johjima, relegated to backup status this past season with the arrival of Rob Johnson, has decided to leave the team.

Johjima opted out of the final two years of his contract, the M’s said. Johjima played this year in the first year of a three-year, $24 million contract. He made $8 million this past season and would have made $8 each of the next two years.

Johjima hit .247 with nine home runs and 22 RBI in 71 games.

“After lots of very deep thought and deliberation, I have decided to return home to resume my career in Japan,” Johjima said in a statement released by the Mariners. “I have had a wonderful experience competing at the Major League level. The last four years have been extraordinary, with great teammates and great coaches. I will always be indebted to the Mariners organization for giving me the opportunity to follow my dream. This was a very difficult decision, both professionally and personally. I feel now is the time to go home, while I still can perform at a very high level. Playing close to family and friends was a major factor. I will miss the Seattle fans and their gracious support. Thank you all.”

Johjima signed as a free agent before the 2006 season, a deal influenced greatly by the Mariners’ Japanese ownership. It was a curious signing from a baseball operations perspective because, even though the Mariners had lost veteran Dan Wilson to retirement, they had drafted Jeff Clement with their first-round pick the previous June.

Johjima came to the Mariners with major concerns over his ability to communicate with pitchers because he didn’t speak English. The bigger problem, however, was that he struggled to connect with the pitchers from a baseball sense when he called games. Johjima’s learning curve was steep, coming from Japanese ball where pitchers primarily “pitch backward” by establishing the breaking ball instead of the fastball.

Still, he had a good season his first year and gave the Mariners much-needed offense, batting .291 with 18 home runs, 76 RBI and setting an American League record for hits by a rookie catcher with 147.

He batted .287 in 2007 but slumped terribly last year, when his average plumeted to .227. Meanwhile, his playing time diminished. The Mariners called up Clement — who also struggled and dealt with knee problems before the Mariners traded him midway through this season — and Johnson was called up late last season and given a strong look.

Johjima suffered a broken toe midway through the past season and Johnson got most of the playing time at catcher. Johnson also won the faith of the pitching staff and, even though the Mariners hesitated to say who was their No. 1 or No. 2 catcher, got most of the playing time by the end of the season.

In September, the Mariners called up highly regarded catching prospect Adam Moore, and he also played well in his limited starts.