toad
蜍 centers on a toad, a specific amphibian. The meaning is narrow and concrete, with no clear abstract extensions.
蜍 combines 虫 (insect/reptile/amphibian) with 余, which likely contributes the sound. The character is used specifically for toad.
The left side 虫 suggests a creeping creature, and the right side 余 looks like a toad's squat body with a bumpy back. Together they form 蜍, a toad.
For ショ, imagine a toad sitting on a show poster: show -> ショ, and the toad is the star of the show.