A One Time Showing Agreement is a commission agreement signed between a buyer's agent and a seller for specific named buyers. Study with Quizlet and memorize flashcards containing terms like What is an important thing to remember about listing agreements?, Describe an open listing. A mediation agreement in Japan helps to define the property that is to be sold, the agent's role in helping to find a buyer for that property. A listing agreement is a contract between a brokerage firm and a seller.