What's with all the weird writing/symbols in the hot springs in 3rei?
The banner looks similar to 武者幟 (warrior flag)

Around AD1600, There are civil war in Japan.
In that time every warrior show that flag to recognize each other.

Wikipedia have some picture of that war.


Or some city selling that flag as goods.


These flags have name of the 将軍 (General) or 紋(the mark of the family).

In that ilier's case, it uses same format, but it doesn't use actual mark or name.
I think it shows "Gil's wrong Japanese stereotype".