As you’re thrown into the world of I Am Setsuna, you will find that it is fairly linear. You’ll be led from one area to the next, with not much of a chance to explore previously visited areas, unless you like to trek back through already cleared dungeons. While exploring all of these places, including the world map, you will come across little sparkles on the ground that can be picked up.
These are ingredients and they can be used to obtain food from specific NPCs. Once you find the four required ingredients, you can talk to the specific person and they will hand over the food item, as well as a recipe, which can be turned into the Chef. Doing such a thing will allow you to purchase that food item no matter where you encounter the Chef.
In addition to that particular NPC, there are a few others in the game’s world. The Magic Consortium guy is the only one that allows you to sell items, including Spritnite, consumables and materials gained from both enemies and from the shiny spots. In turn, you will be able to purchase new Spritnite from him, depending on what materials you have sold. The Blacksmith will let you purchase new weapons, talismans and even weapon-upgrading tempering items. The Apothecary sells usable items.
Note: There are no inns in this game, so the only way to heal is via items. Also, when a character levels up, they will fully heal.