Signed flag cups
The phrases on this flag are: The Glory of the Country,
Banzai to the Japanese Empire,  Loyalty & Bravery'.

The other characters read 'Heavy Transport 3rd Regiment
Commemorative'.
The phrases on this flag are: 'The Glory of the Country, Banzai
to the Japanese Empire, Complete Victory'.

The other characters read 'Victorious Return Commemorative'.
Japanese soldiers often were given a silk or cloth flag
signed by friends and family. He would then take it with
him to battle. It would supposedly protect him from
danger. This practice was widespread, so much so
that it might be safe to assume that most soldiers had
one. However, strangely enough, these rarely appear
on sake cups. Perhaps because they were too
personal, but that explanation seems a bit weak. The
flag design might have been hard to make, though.
The examples I have here have similar patterns stamped in. But upon closer
examination, you'll see that the phrases are different. Perhaps these phrases
were stamped in after the main pattern had been. At any rate, the kanji within the
flag do not appear to have been hand-written.
The phrases on this flag are: The Glory of the Country,
Banzai to the Japanese Empire,  Loyalty & Bravery'.

The other characters read 'Victorious Return
Commemorative'.
The phrases on this flag are: 'Long Life to the Military, Banzai to
the Japanese Empire, The Invincible Imperial Army, Complete
Victory'.

The other characters read 'Victorious Return Commemorative'.
The phrases on this flag are: 'The Glory of the Country,
Banzai to the Japanese Empire, Complete Victory'.

The other characters read 'Victorious Return
Commemorative' and in blue is the soldier's name:
Hachikubo.