In Chat Plus, you can display [Chat Unread Badge] to users. To display, you have to set these below.
※This function can only be done above Business Light Plan.
(1) Click on the setting button on the upper right of the management page. 
(2) Click on [Chat]>[Design]>[Menu] on the left side of the screen. 
(3) Click on [Stand by] tab. 
(4) Click on [Detailed Setting]. 
(5) In the section [Option], check in the box [Display Unread Badge]. 
In the section [Unread Badge], you can set badge's background color, letter color, and size. 
(6) Click on [Update]. 