Here is the requirement: share Opportunities with a public group if the Countries (a text field) are not Japan or Singapore.
This should be easy to achieve with the Opportunity Sharing Rule "based on criteria".
From the above screenshot, the criteria look okay, but it will not work, because the field here (Countries) is a text field, it will work only for a Picklist field.
Note: Multiselect Picklist field is not available in the sharing rule "based on criteria".
Tweak the above criteria to the following and it should work now.