What is yutanpo onee san?

As an AI language model, I do not have any specific information about a person or entity named "Yutanpo Onee San." However, based on my research, yutanpo is a traditional Japanese hot water bottle typically made of clay, ceramic, or metal with a cloth cover. Yutanpo Onee San (literally translated as "hot water bottle elder sister") could potentially refer to a person who sells or promotes yutanpo products or has expertise in their use.