The defending champion Tochigi Brex fell to 2-3 to open the new season, losing 76-70 to the visiting Chiba Jets on Saturday afternoon.
Chiba sealed the victory at the free-throw line in the fourth quarter, converting 10 of 11 shots, including three apiece by Ryumo Ono and Yuki Togashi, both of whom attempted shots in the final stanza.
The Jets (4-1) held the hosts to 3-for-17 shooting in the fourth quarter.