Brazilian import Lorenne Teixeira led Ageo Medics with 17 points, making two blocks and two aces.
Mami Uchiseto also scored 17, all coming from attacks, while Yuka Sato drilled 12 of her 21 spike attempts as Saitama improved its win-loss record to 6-5.
Jaja Santiago hit eight spikes from 16 attempts and fired an ace to finish with nine points.
Santiago and Ageo Medics try to double their victory and keep Toyota winless when the two teams meet again on Sunday.
American import Kelsey Robinson led Toyota with 19 points from 18 attacks and an ace. Toyota has yet to win in 11 tries.
Mihoko Yabuta and Sakura Kurosu chipped in 13 and nine, respectively.
Ageo Medics improves its win-loss record to 6-5.
Meanwhile, Bryan Bagunas and Oita Miyoshi fell to JT Hiroshima, 19-25, 26-28, 28-30, at the Showa Denko Martial Arts Sports Center.
JT Thunders kept seventh spot with a 4-7 record while sending the Weisse Adler to their ninth loss in 11 matches in ninth place.
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