"I <3 Hermoine. Ink by @indiangiver," Franco posted on Instagram Wednesday featuring the tattoo.
The black and white selfie also showcases an elaborate American eagle tattoo located on Franco's bare chest.
The new ink however does appear to be a fake. The artist credited with the work, Cheyenne Randall is known for using Photoshop to add ink to pictures of celebrities. Randall's own Instagram account features the same photo Franco posted with the hashtag "#shoppedtattoos," referencing the photo editing software.
Franco and Watson both costarred together in the 2013 comedy hit, This Is The End.