This piece of equipment might look quite unusual to people from other countries.
It is a "cargo" unit used during base open-house events. It was built by Self-Defense Force personnel to allow the general public—especially children—to have a hands-on experience with tanks.
Normally, there are very limited areas on a tank that one can actually board. However, because the Self-Defense Force wants as many children and members of the public as possible to experience and gain a better understanding of these vehicles, they utilize equipment like this at such events.
In a sense, this is the kind of equipment that can only be used precisely because we are living in a time of peace.