[Nyororin]

There is Pizza Hut coverage for most of Nagoya, along with a few smaller but good places - if you avoid the crap that is Aoki`s and Dominos Japan.
However, you say you`re going to be in Kasugai or Komaki - both of which are not Nagoya, so will cut down your choices quite a lot.

You can find real cheddar cheese in almost every Jusco (Aeon) around Nagoya, and wheat bread is available in bread shops - just not usually in the regular bread corners in grocery stores. For the mustard, I will suggest Jusco again. They stock the classic yellow stuff along with other non-Japanese kinds.