Q.
The character is placed in 3D space.
And I tried to change the character’s Transform to rotate it, but it doesn’t rotate.
A.
(Some features have been improved since your reply.)
When you enable the “Billboard” option to place a character in 3D space, the rotation of the character cannot be controlled by an external script.
This is because the billboard operation includes the rotation of the Transform.
However, it is not impossible to rotate the character.
You can create an empty parent GameObject and rotate that GameObject instead.
This will cause the “Billboard” operation to recognize the parent GameObject and perform rotation operations differently.
You can find some options related to this in the following manual.
https://rainyrizzle.github.io/en/AdvancedManual/AD_BillboardPers.html