This case study combines two typologies simultaneously—a net cover and a prefab. As observed during multiple urban explorations, net covers of such kind often serve as a DIY solution for some kind of practice—baseball, basketball, football, archery, etc. In this case study, too, the net cover proved to serve as a small golf practice field—it is meant to prevent the golf ball from flying off the rooftop.
The prefab structure in this case serves as a storage space—for the golf equipment as well as miscellaneous household items that are not in use at the moment (e.g. summer futon (traditional Japanese style of bedding).
Usually, prefab structures like the one here are additions to the building which have been made after its completion. Often, they are structurally, material- and finish-wise drastically different from the building they sit above. However, this is different in the case, where according to the interviewee—a resident of the 4th floor of the building—the structure has been placed on top of the building since the very beginning (28 years ago), and it has been in use by the interviewee since then. Interestingly, this is contrary to the conclusion one might devise from simply observing the structure and the rooftop. A logical assumption would be that the structure had been added after the building completion as it bears no structural connection to the rest of the building—an impression reinforced by the fact that additional steps made out of chequered steel plate were placed to access the rooftop, which, perhaps, was not planned to be frequently accessed.
Among the benefits of using the rooftop space the interviewee mentioned the fact that the rooftop space can be used at any time without having to go out of the building. This is a very strong point for rooftop spaces, because the Japanese who live in such urban conditions do not typically have a satisfactory open private space in their dwellings (in case of mansion residences)—space such as balconies or verandas, if present at all, are typically quite small, mostly used for practical purposes such as laundry drying.
Occasionally, people would grow plants on their balconies, but even those are often required to be lower than the railing height to preserve the homogeneity of urban facade. Smokers cannot use the balconies either as it is usually prohibited to smoke there. All these factors are not encouraging the use of the balconies as a private leisure space, and it is certainly very rare (unlike in the West) to see people in Tokyo spending long time on their balconies or verandas, using the space for anything other than taking care of the laundry/plants or stepping outside only for a moment to check the weather. This is where rooftop spaces can provide a great opportunity to have a private or a semi-private open space for any activities for which there is otherwise no room for.