BRENDA

1.  Tokyo concert :  Red light & paper plain
2.  Beijing concert :  a lot of stuffs (balloons & small flag...& etc.)
3.  Guangzhou event :  blue colored hair scarf with his name

not too expensive but, more efficient stuffs,

what about blue colored balloon with his name?
or, special hair band or scarf....  

if any asking to the fans, they should bring their national flag, so, it could be attention by media.