Indicating mandatory field without labels
I have multiple forms in my application. I have used minimalistic view where there are no explicit labels for fields. For example, check wireframe displayed below:
Here First Name, Last Name, and Username are mandatory fields.
However, due to "some" guidelines, I have to mention which fields are mandatory before the user would fill out the form.
What is the best way to indicate that these fields are mandatory?
I do not want to add labels to the text boxes just for this purpose, as I have used the same styling everywhere.
Here are two options that I tried: