Sanshisan 三十三 [Thirty-Three] is a transliteration of Trāyastriṃśa in Sanskrit or Tāvatiṃsa in Pali. “The Trāyastriṃśa heaven is an important world of the devas in the Buddhist cosmology. The word trāyastriṃśa is an adjective formed from the numeral trayastriṃśat, “33” and can be translated in English as “belonging to the thirty-three [devas]”. It is primarily the name of the second in the six heavens of the desire realm in Buddhist cosmology, and secondarily used of the devas who dwell there.” (Wikipedia)
In this story, it is used loosely to refer to all the heavens.
