FULL PRODUCT VERSION :
java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b25)
Java HotSpot(TM) Client VM (build 25.40-b25, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.2.9200]

A DESCRIPTION OF THE PROBLEM :
It has been announced that the issue JDK-8051420 and JDK-8054904 duplicate and have been already resolved on 7u71.
But when Windows logon account name is Japanese, home directry is Japanese also.
And when this user activate application from Java Web Start, "CouldNotLoadArgumentException" occures and cannot start.

REGRESSION. Last worked in version 7u65

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Log in on administrator account
2. Chose Japanese language from the Language bar
3. Create user アスカ太郎
4. Set "Current language for non-Unicode programs" to Japanese (Japan) inside:
Control Panel -> Clock, Language, and Region -> Region and Language ->
Administrative (tab) -> Language for non-Unicode programs -> Change system locale
5. Log in on アスカ太郎 account
6. Input URL into browser and start with jacaws.
 http://docs.oracle.com/javase/tutorialJWS/samples/deployment/dynamictree_webstartJWSProject/dynamictree_webstart.jnlp
7. 4. Error occures.
CouldNotLoadArgumentException[ 指定されたファイルまたはURLをロードできませんでした: C:\Users\ﾒ鬮~1\AppData\Local\Temp\javaws2]
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Application us loaded correctly and start.
ACTUAL -
"CouldNotLoadArgumentException" occures and cannot start.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
CouldNotLoadArgumentException[ 指定されたファイルまたはURLをロードできませんでした: C:\Users\ﾒ鬮~1\AppData\Local\Temp\javaws2]
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Create logon account with single-byte characters and switch logon account only when using the application.
This is not a realistic workaround as it is too much of work.