I recommend you buy tasty instant noodles UMAKACCHAN うまかっちゃん as a souvenir.
The soup is made with pork bone and many kinds of flavors are available.
UMAKACCHAN is extremely rare in Tokyo!

It is difficult to buy them at the supermarkets in Tokyo, because the manufacturer retails them mainly western Japan, such as the western regions of Osaka 大阪 and Kyoto 京都. One reason for this is the preference of pork soup that the people who live in Kyushu 九州 region have. It is one of their local foods.
When you are traveling around western Japan, you should try to find them.

This blog introduces 6 kinds of flavors below.
Manufacturer’s suggested retail price : 1 pack 105 yen (not including tax)

1. This original flavor is the most favorite one for me.

2. Shrimp and miso flavor 海老みそとんこつ

3. A little bit spicy からし高菜風味

4. Smoky 黒豚とんこつ 焦がしねぎ風味

5. Heavy and rich soup 久留米風とんこつ

6. Garlic flavor 火の国流とんこつ 香ばしにんにく風味

A 5-pack of the noodles
Manufacturer’s suggested retail price : 525 yen (not including tax)

House Foods Corp.
ハウス食品 (Hausushokuhin)

Website of UMAKACCHAN うまかっちゃん
http://housefoods.jp/products/catalog/cat_1,nood,ramen,uma.html (in Japanese)

Top page
http://housefoods.jp (in Japanese)

Where to buy in Tokyo
I found the noodles in these chain stores Don Quijote ドン・キホーテ in central Tokyo. When I went there, the original one and spicy one were displayed there.
(English information)
A 5-pack of the noodles costs about 400 yen at Don Quijote stores. It might be sold out though.