What Is Eriku's Ability?
From Antoine Bauza (the designer of Tokaido):


  Eriku can look at the first Meal card of the deck and choose to buy it
  instead of one of the regular cards. At the first Inn, He can also
  look at the top card and buy it (no regular hand here of course). So
  He can eat one more meal than the others... Official rules and wording
  will come on Funforge Website I guess...


So at the first inn, presumably before setting off, Eriku can look at the top card of the meal deck and choose to buy it. Then, on arriving at each subsequent inn, he may include the top card of the meal deck in his choices of what to eat.

Source:
http://www.boardgamegeek.com/thread/1063646/what-is-erikus-ability