Robbie Deans' Panasonic Wild Knights are also unbeaten. Sam Whitelock, Chris King and Craig Millar head their New Zealand playing contingent.
Kieran Read, Ryan Crotty, Liam Squire and Matt Todd are among the many other notable New Zealanders spread across the 16-team league.
Steve Hansen and Simon Cron (Toyota), Todd Blackadder (Toshiba), Dave Dillon (Kobe) and Alando Soakai (Kubota Spears) are other Kiwi coaches in the Top League.
Jamie Joseph is also Japan's national coach.
Japanese clubs have allowed foreign players and coaches to return home at different stages, leaving some stranded in Japan.
As countries such as New Zealand adopt travel bans and lockdowns, organisers were left little choice but to cancel the remainder of the season.
"The global expansion of the coronavirus has prompted many governments, including New Zealand and Australia, to repatriate their nationals from abroad, resulting in many of our players returning to their home countries," the league said in a statement.
The league listed the operations of parent companies as another reason for the cancellation.
"As all clubs in Top League are corporate, the impact on companies could be very serious if athletes and staff were to become infected."
All tickets purchased for cancelled games will be refunded.
After initially halting the competition in response to the coronavirus outbreak, Top League suspended games in early March for the rest of this month following the arrest of a Hino Red Dolphins player for alleged illegal drug use.
The league said at the time it would use the break to conduct "thorough compliance education" with clubs after Hino's New Zealand-born forward Joel Everson was arrested on March 4 for cocaine use.
The cancellation of the Top League comes as Canada pulls out of attending the Tokyo Olympics and Australia has told its athletes to prepare for the Games to be postponed until next year yet organisers continue to delay making an official decision.
