Octopus-shaped slides are very common in children’s playgrounds across Japan, popular for their whimsical, maze-like designs. Installed by the Maeda Company in the 1960s, the tako-no-yama or "octopus mountain" spawned a brood of hundreds of similar slides around Tokyo and beyond in the next decades, and there is even one of those in Copenhagen today.

But debates arise when it comes to which park was the trailblazer of this trend. According to the most popular theory, the first octopus slide was installed in Shin-Nishiarai Park in Adachi Ward, Tokyo, in 1965, after a sculptor's initial concept of abstract playground equipment was rejected by the city council. As a compromise, the sculptor added an octopus motif to his design and the rest is history.

Another theory is that the octopus slide was made popular not by the Shin-Nishiarai Park one, but by the ones at Shinmei Children's Park in Shinagawa Ward, which was installed in 1968 also by Maeda. Only one of the two slides in Shinmei has survived and was relocated to another park.

The Shin-Nishiarai octopus slide, on the other hand, is the oldest surviving specimen (no matter whether it's the very first or not) and has stood in the same spot for many decades since its installation. Recently repainted in 2019, the beloved local icon now takes an outer space theme, the winner of a design competition.