The person who runs or owns a shop; the proprietor or shopkeeper.
小さな居酒屋の店主は、毎朝仕入れに行く。
The owner of the small izakaya goes to buy supplies every morning.
店主にレシピを教わって、この店の味を守っている。
I learned the recipe from the proprietor and preserve the taste of this shop.
店主のおすすめメニューをいただきます。
I'll have the proprietor's recommended dish.