Nikumaki ( Meat Roll) --- the inside is steamed white rice. It was very good. It was originally snack cooked and eaten by kitchen staff. Then since it was so good it became popular in Miyazaki prefecture and came to Tokyo.
In my town, Shimokitazawa, this shop is selling two kinds. One is regular and the other is with Cheese. Both are 300 yen.
Friday, Saturday and before Holiday:
It is near Honda Theater.