The Filipino guard keyed the visitors' 16-6 run to fight back from a 74-67 deficit in the final 4:42, draining the crucial freebies that pushed Shiga up, 83-80.
Trey Jones scored two for Gunma, but Ravena tried to respond with a dagger three. He, however, muffed his long bomb and was whistled for a foul on the rebound play, leading to Jones cooly sinking the go-ahead freebies in the last three seconds.
Ravena had one last chance to salvage the game, but his jumper at the buzzer can't find the bottom of the net.
It was a tough finish for the import which poured seven of his 17 points in the last four minutes, as well as seven assists, four rebounds, and three assists as the Lakestars suffered their 13th straight defeat to sink to 10-30.
Sean O'Mara paced Shiga with 27 points and 10 rebounds as it turns its attention to league leader Ryukyu Golden Kings at Okinawa Arena this weekend.
Michael Parker carried Gunma (17-21) with 22 points, nine rebounds, and two blocks in the win.
Justin Keenan got 19 points, eight boards, and eight dimes, while Jones had 17 points, six rebounds, and three assists to snap a three-game losing streak.
Thirdy Ravena and the Neophoenix fall to 8-34.
Meanwhile, Thirdy Ravena and the San-En NeoPhoenix stumbled to their third straight loss with a 91-65 defeat to Shimane Susanoo Magic at Toyohashi City Gymnasium.
The Filipino guard was held to just six points, two rebounds, and one assist as the home team fell behind early and stared at a 52-31 halftime deficit.
Max Hisatake was the lone bright spot for San-En with 20 points, 18 boards, and two steals, but those numbers weren't enough to help the NeoPhoenix get swept by Shimane in this three-game series to fall to 8-34.
Nick Kay led the balanced attack for Shimane, spearheading the six players to notch in double figures with his 19 points, six assists, five boards, and two steals.
Perrin Buford and Nyika Williams had 16 each, as former Meralco import Seiya Ando added 10 points, five dimes, and two boards as the Susanoo Magic stretched the lead to 29, 91-62, and rise to a 34-10 card.
Things won't get any easier for San-En as it plays Osaka Evessa at Ookini Arena Maishima this weekend.
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