Because of this origin, the character 升 came to represent 'masu' (a square, wooden measuring cup), and also sho, which is the unit of the volume measured with the masu, and in addition, it now represents the Japanese verb 'noboru' (means 'rise'), which came from the act of scooping something up with a ladle.
そこから量を量る「枡」の意味、およびそれによって量られる容積の単位を意味するようになった（これとは別に、柄杓で物を掬い上げることから「のぼる」の意味もある）。