storey, stair, counter for storeys of a building
階 centers on layered levels in a structure: a storey of a building, a stair connecting levels, or counting floors. The idea is always about stacked horizontal divisions.
階 combines ⻖ (hill, mound, or steps) with 皆, which likely contributes the sound. Together they suggest a stepped rise like a stairway or tiered levels.
The left side ⻖ looks like a stepped hill or mound, and the right side 皆 suggests a row of similar things. Picture a staircase where each step is one of many identical levels.
For カイ, imagine climbing stairs to a high floor and looking out at a calm bay: bay -> カイ, and each storey gives a better view of the bay.
storey; story; floor
stage; step; phase
stairs; stairway; staircase
(social) class
class; level; stratum; layer; hierarchy
top floor
scale
upper floor; upstairs
lower floor; downstairs
basement; cellar
each floor
number of stairs or stories (storeys)
court rank
two-factor authentication
class hierarchy
data hierarchy
data staging
data transfer phase
House of Cards (TV series)
Beaufort scale (of wind force)