mezzanine floor; mezzanine
Refers to an intermediate floor between main floors of a building, often in commercial or public spaces.
このデパートの中二階にはカフェがあります。
There is a café on the mezzanine floor of this department store.
Compound of 中 (middle) + 二階 (second floor), literally 'middle second floor', referring to a floor inserted between two main levels.