The SoftBank Hawks' bid for a fifth straight Japan Series championship begins in earnest on Friday when Nippon Professional Baseball's two leagues kick off their regular seasons in six games across the country.

The Hawks, the defending Pacific League champs, have won six of Japan's last seven championships, but this year may not have the PL's most potent starting pitching. On paper, the Rakuten Eagles appear to have Japan's best pitching rotation with the return of former ace Masahiro Tanaka and the addition of rookie lefty Takahisa Hayakawa.

In the Central League, the Yomiuri Giants are on the hunt for a third straight pennant, and a 23rd Japan Series championship that would end a franchise-record eight-year stretch without one. The Giants have not won a Japan Series since 2012 or a Japan Series game since they beat Tanaka in 2013 to force a Game 7.

Masahiro Tanaka of the Rakuten Eagles pitches against the Yakult Swallows in a preseason baseball game in the Okinawa Prefecture city of Urasoe, southern Japan, on Feb. 27, 2021. (Kyodo)

Tanaka's return after seven years with the New York Yankees was the big news of the offseason.

The right-hander, who went 24-0 in 2013 to lead the Eagles to their only Japan Series championship, is coming back in the hopes of lifting northeastern Japan's spirits again 10 years after the region was devastated by the March 2011 earthquake and tsunami.

Eagles' general manager Kazuhisa Ishii has added field manager to his portfolio. The Eagles' offense is nothing special, apart from annual MVP candidate Hideto Asamura, but Tanaka and Hayakawa add to an already solid starting rotation.

With NPB teams limiting games to nine innings this season due to the coronavirus, the Eagles' starting pitching strength could more than make up for any middle relief deficiencies in Sendai.

Star center fielder Yuki Yanagita, the big wheel behind the offense of the SoftBank Hawks, shows batting in a preseason game at Fukuoka's PayPay Dome on March 20, 2021. (Kyodo)

The Hawks were unable to sign big lefty Matt Moore, but their starting pitching, behind ace Kodai Senga, might be as strong as the Eagles and will be backed by the PL's best defense, a strong bullpen, and outstanding offensive power and speed.

SoftBank opens its season at home against the Lotte Marines, last year's second-place club, while the Seibu Lions, league champs in 2018 and 2019, will host the Orix Buffaloes. The Eagles will be at home to the Nippon Ham Fighters, kicking off the season in a 4 p.m. start.

With the government asking businesses in the Tokyo area to close by 9 p.m., the five teams based there will begin their early-season night games before 6 p.m.

NPB is trying to complete a full 143-game schedule after jettisoning its all-star series and interleague play last year. Both leagues will return to the three-team, two-tier Climax Series playoffs to determine its Japan Series contestant this year. In 2020, the CL went without playoffs, while only two teams made the PL's slimmed-down postseason.

The Giants have ace pitcher Tomoyuki Sugano back for another year after he declined offers to sign with major league clubs over the winter. They open their season at home against the DeNA BayStars, who replaced Japan's first Latin manager, Alex Ramirez, with their 2020 farm manager and former ace Daisuke Miura.

The Yokohama-based club's offense is handicapped at the start of the season without two-time CL home run champ Neftali Soto and Tyler Austin, who hit 20 home runs last year in just 65 games. The two, along with the club's other imports, were blocked from entering Japan during the recent state of emergency and missed all of spring training and the preseason.

The Hanshin Tigers will have to wait for KBO home run and RBI leader Mel Rojas Jr. and Raul Alcantara, who went 20-2 to lead that league in pitching wins in 2020, but rookie outfielder Teruaki Sato could be an impact player.

Sato, a powerful left-handed-hitting slugger, whom four teams named as their first draft pick in 2020, hit six home runs during the preseason with good power to the opposite field.

The Tigers and Yakult Swallows will kick off the CL season in a 5:30 p.m. start at Tokyo's Jingu Stadium, where hard-throwing but enigmatic right-hander Shintaro Fujinami will start for Hanshin.

The Chunichi Dragons, who finished third last year, will open against the Carp at Hiroshima's Mazda Stadium, but without Sawamura Award-winner Yudai Ono on the mound after the lefty got a late start to his spring throwing program.

With the PL having won the last eight Japan Series, the last two in four-game sweeps by the Hawks over the Giants, much of the conversation over the winter was about the PL's recent dominance. That discussion will likely be rekindled on May 25, when interleague play resumes after a one-year hiatus.