Asian champions Japan, which fielded a young squad in this tournament, made a poor start in the opening set against Vietnam who ranked sixth at the recent 18th Asian Games in Indonesia.
Tran Thi Thanh Thuy, who is 1.90m tall, shone in the first set to help Vietnam win 25-20.
Both teams made a solid start to trade points from the beginning of the second set which saw the score tied at 8-8. After that, Vietnam found themselves two points clear at 22-20.
However, their lead was short-lived as Japan stormed back with aggressive spikes and well-organised defence to surge ahead of the experienced rivals and win the hard-fought set 25-23.
The third and fourth set saw the Japanese girls controlled the game. They covered the court well for attacks and blocks and won 25-12 and 25-23.
In this game, Miwako Osanai scored 19 attack points for Japan, while Shuri Yamaguchi and Shiori Aratani added 14 and 12 points respectively. Thuy led Vietnam with 16 points.
Vietnam will next meet Kazakhstan for the fifth-10th places round.