I have been interested in playground equipment since my first child was born 10 years ago and I started going to the park frequently. Since 2020 with the start of the Corona disaster, my interest in playground equipment has increased even more. We went to unpopular parks in the suburbs at a time when we had to avoid commercial and crowded places in our daily lives, and we went to parks more often in the evenings when they were less crowded. While daycare and elementary schools were closed, we went there almost every day.

　　When I went to various parks and observed children at play, I observed many interesting forms of behavior. Some playground equipment was crowded with people who communicated in various ways while playing on it, while others drew no interest at all, so kids played there for a little bit then moved away. Some playground equipment encourages people to compete with each other. Of course, children are not playing with a rational mind, thinking that this equipment encourages competition or that they can enjoy playing with others. The objects are individually guiding the movements and communication of children who unconsciously interact with the playground equipment.

　　As the number of people infected with the new coronavirus has decreased, I have often visited indoor playgrounds during periods of intense heat or harsh winter days, and there I find the same interesting "communication" between playground equipment and children, or "objects and bodies." The shapes and functions of playground equipment can bring children together or separate them, make them compete or get along with each other. For me it is very interesting and it has made me want to think about the ontology of playground equipment. This is why, as part of my "Rita project" for this research center, I am currently conducting fieldwork in various parks to observe how children’s play is mediated by playground equipment.

　　Playground equipment is an object that mediates among people, and it strongly reminds us of the fact that Rita that is generated between "people + objects + people." Everyone has experienced playing on playground equipment when they were children; it is an entity deeply involved in children’s play and learning in their daily lives. I would like to write a book about the ontology of playground equipment in relation to Rita, but for this article I will introduce an ordinary piece of playground equipment in a local park. In order to capture the Rita-affording characteristics of this playground equipment, I will also introduce another kind of playground equipment with similar functions.

　　First is a kind of jungle gym that kids play with by turning a globe-like sphere (its official name is Globe Jungle). This popular old-fashioned playground equipment had long been installed in school yards and parks and been loved by children. In the past, thrilling spinning playground equipment like this was seen in many places, but in recent years it has been removed due to the risk of accidents, and the numbers of such equipment have been drastically decreasing overall. Nevertheless, there is no doubt that this is one type of playground equipment that thrills children.

　　Mitsuru Senda, an environmental architect, advocates the "Circular Play System Theory," and has been involved in the design of a wide range of environments, including not only parks but also schools, public facilities, and towns. His theory emphasizes "Vertigo" play behavior in playground equipment, and the Globe Jungle is none other than a piece of playground equipment that triggers a "vertigo" experience. There is a very small park with this playground equipment in my neighborhood, which my children call "Guru Guru Park." [In Japanese guru guru is an onomatopoeia for the feeling of spinning around.]

　　The unique feature of this playground equipment is that it has a clear boundary between the inside and the outside. Of course it is possible for a single person to spin the equipment and then jump on it, but in general, the children are divided into two groups: those who spin the equipment and those who are spun by others. Observing children’s behavior, it is usually the case that while many children enjoy the thrill of spinning the wheel by spinning it as fast as they can, many others do not, but instead start to shout "Stop it!" or even half cry out, saying "I’m scared!" The people being spun around get more scared than they had imagined, and even if they want to get off, it is difficult to do so at high speeds. Sometimes, the person who spins the wheel even enjoys watching the fright of the person being spun around, and if the prank goes too far, the fun cannot continue.

　　Another thing that should be mentioned is that the shape of this playground equipment sometimes affects people in exclusionary ways. When one group is playing in the "Globe Jungle," other groups seem to have difficulty intervening and entering this play area, and they have to just wait their turn. In other words, when viewed from a group perspective, the shape [and mechanism] of these rotating playground items seems to "sever" the possibility of relationships among people, rather than bringing strangers together.

　　There is another park in the neighborhood that has a similar but slightly different type of spinning playground equipment. It is a doughnut-shaped rotating device that brings people together in a completely different way than the "Globe Jungle." I am not sure what it is officially called, but I will call it the "Doughnut Playground Equipment" (DPE) here. At first glance, it looks simple and not particularly eye-catching or luxurious, but I have not seen this type of equipment very often. There are slides and sandboxes in the park, but the children call this park "Doughnut Park" (it seems the "DPE" has most symbolic power for them). It may be difficult to convey what the fun is, but this playground equipment is very interesting. Observation of children’s play behavior when using the "DPE" suggests that the Rita-affording potential of this equipment is extremely high.

　　First of all, the "DPE" cannot be turned as quickly as the "Globe Jungle." It is heavy and requires a certain amount of force to spin, so it is not very enjoyable to play by yourself. Therefore, multiple people can ride it, switching places, turning it and getting on and off as children move about. Since it requires a lot of pushing power, children straddle it when they get tired, and when someone gets on, other children get off and start spinning it so as not to interrupt the movement. In a manner of speaking, the play in this place is established by the cooperative power of the children involved with the "Doughnut Playground Equipment."

　　Interestingly, even if the equipment is spinning in the middle of someone else’s play, other groups may quickly jump on and play together. As mentioned earlier, it is difficult for another group to enter the "Globe Jungle" while it is spinning, and there is little interaction between different communities. In a sense, the equipment itself even creates a sense of occupancy and exclusivity. On the other hand, the shape and movement of the "DPE" draws together children who do not know each other, and there is a sense of exchanging strength as they help and amuse each other without words. Other factors that contribute to the popularity of this playground equipment are its rounded shape and marvellous width. When I observed children playing on it, I saw small children lying on their backs, clinging to it using their limbs to embrace it. They hold on to it with their legs and hands, becoming one with the equipment and experiencing "vertigo" with their whole body.

　　The fact that this playground equipment is designed in a "diagonal" shape should also be considered very important. Due to the gravity created by the oblique shape, there are areas where force is applied and areas where it is released, and there are times when it can be "moved" and other times when it "moves" on its own. The "Globe Jungle" is a type of playground equipment that the people outside "turn" voluntarily and actively, while the people inside "are turned" passively. On the other hand, the "DPE" is very ambiguous. The act of one person pushing upward for enjoyment may become another person’s pleasure, and the act of holding on with one’s whole body and descending according to gravity may unintentionally help the person pushing the equipment up. Just when a child thinks he or she is turning the playground equipment by himself or herself, it may turn due to other forces, or when is or her action ought to be turning the "DPE", it may suddenly be turned by the actions of others. In other words, "movement," which lies somewhere between "making something move" and "being moved by something," constantly intervenes in play. Perhaps there is a kind of latent Rita in the middle voice (Chudotai) nature of the children’s play. The shape and function of this playground equipment seem to bear a hint of Rita or an inclusiveness that welcomes others. Although it is just an ordinary set of objects in our daily lives, playground equipment is truly profound.