The inclusion of the number "13" in the keyword is one of its most specific filters. In the context of U-15 idol media, the model's age is often the primary selling point. Given the release date of this DVD—May 20, 2012—and the fact that performers in this niche are often around that age, it is highly probable that "13" refers to the age of Sasaki Miyuu at the time of the video's production.
Common for the series, these are often filmed in tropical or scenic outdoor locations (such as Guam) to highlight the "youthful" and "innocent" theme of the "Pure Smile" brand.