The Akita Northern Happinets pounded the host Tokyo Cinq Reves from start to finish in Friday's series opener in Inagi.
Seven Akita players scored in double figures as the Happinetes demolished Tokyo 108-59.
Kenta Tateyama paced the visitors with 20 points, knocking down 4 of 6 3-pointers. Richard Roby added 16 points and four steals. Shigehiro Taguchi and Ruben Boykin each had 15-point nights. Deshawn Stephens poured in 12 points and grabbed 15 rebounds, while former Wake Forest big man Tyran Walker added 10 points and 16 rebounds and Yuto Otsuka chipped in with 10 points.
Akita floor leader Akitomo Takeno had eight points and seven assists in the rout. Otsuka played a team-high 26 minutes.
The Cinq Reves (4-19) were handed their eighth straight loss, and coach Motofumi Aoki's club has lost 17 of its past 18 bj-league games.
The Northern Happinets (19-4 overall, 12-1 away) extended their winning streak to seven games.
Tokyo trailed 29-10 after one quarter and 52-24 at halftime.
Akita took a 76-41 advantage into the final period.
Will Foster scored 14 points and pulled down 12 rebounds for the Cinq Reves. Jemal Farmer had 13 points.
Tokyo shot 25-for-76 from the floor.
Akita out-rebounded the hosts 54-37.