Where can I find a guitar hero Metallica Competition?
@Milano Game Station you can go with a group of your friends and play it there.
Where can I find a manga shop?
@16:9 Widescreen has a whole manga section that holds great deal of titles from the different manga series.
Where can I find a place that sells punching bags?
Check with @Olympiad Sporting Goods. They almost have everything
Where can I buy balloons?
You can find some @Smiley Balloons or @BalloonzMania. I like both of them!