This material is an unofficial set of notes for people who plan to attend, or are considering attending, a winter ultra- crowded market event held in Japan. This is not an official manual or a collection of rules. However, it is precisely because these behaviors and considerations have been respected among participants that large Japanese fan events have been able to operate safely for many years. Japanese fan events are not simply places to shop. They are participatory events built through cooperation between creators, participants, and organizers. For visitors from overseas in particular, there are many things that may seem obvious but are often unfamiliar, such as preparing cash, how to line up, how to move within crowds, and how proxy services and reselling are viewed. This material explains these unwritten customs and ways of thinking as cultural context in a clear and easy- to- understand way. Nothing here is a law or a requirement. However, whether you understand these points or not can greatly change your experience of the event. Please use this as a small collection of tips to help you participate safely, comfortably, and with respect for others. This material can be read not only by those who plan to attend, but also by those who are simply interested in going someday. It can be used to understand the atmosphere and culture in advance. If you find the content helpful, please feel free to share these notes within your community.