Malls in Tokyo, jpop merchandise..?

Hi. I'm hoping someone can give me some mall recommendations in tokyo. I'm a 22 year old girl interested in buying clothes, shoes, bags..etc. I don't know where to shop when im in Tokyo.

Also, im looking for a place that sells jpop/jrock idols' merchandise, like posters, keyrings and stuff. I found a little shop like that at takeshita douri in harajuku, it had all Johnny's' stuff.. Any other places?

My favorite mall is connected to Kawasaki station (Kehin-tohoku, Tokaido, and Nambu lines)

When I went to Japan I shopped at marui and isetan. They as well as most other large department stores had my size, and I'm about a 20/22 UK, 20 US. I brought a lot of scarves (I think Japanese women like scarves a lot -- I do too, so it was refreshing!) but I didn't buy any shoes. I saw a lot of nice bags too. They had plus sized shoes at Isetan.

Another really good place is Sunshine 60 building in Ikebukuro. Follow the signs from the JR station where Seibu is. I spent 3 hours there and there are tons of floors, but in the 3 hours I spent there, I just barely got to B1!! (I think there's B2, B1, 1st floor, etc.) In addition, there's plenty of places to eat there as well as along that street. There's a place called Alta Market that takes up a lot of it. I got a few things there.

Seibu isn't bad, there are lots of accessories there. If you're smaller, you can find clothes there easier than I could!

My penpal recommended Lalaport Toyosu which is in ... Toyosu. You can reach it by train station easy apparently. They have a website in English if you google them. (I'm not sure how URLs show up on Japan-guide.)

Hotel Venus is also recommended, but I've forgotten where that is, I didn't get to go.

Do they have a giant Hello Kitty store in Japan?