The buyer; the person who purchases something or is on the purchasing side of a transaction.
買い主が見つかって、家の売買が成立した。
A buyer was found and the house sale was completed.
買い主は支払い方法について売り主と相談した。
The buyer discussed payment methods with the seller.
商品に問題があったため、買い主は返品を求めた。
Because there was a problem with the product, the buyer requested a return.