係

It is a phono-semantic compound made up of:

人 (인, “person”) — providing the meaning (something involving people);

系 (계, “to connect, system”) — providing the sound.

The Shuowen Jiezi (説文解字 shuōwén jiězì) explains it as “that which ties one person to another.” From this, the meaning expanded to “to be related to” or “to have a connection with.”

Although 係 and 系 differ in pronunciation, they have long been used interchangeably, and in Simplified Chinese, the two were merged under 系.