The number '33' has a connection to the deity Kannon and Buddhist texts such as the Lotus Sutra describe how she can present herself in 33 different forms in order to save the sentient beings of the world.
「33」は観音に縁のある数字で、『法華経』等に観音菩薩が33種の姿に変じて衆生を救うと説かれることによる。