After having spent five years studying at the Beaux-Arts school in Angers, Johann began working in film and advertising as a set designer. Ten years later, he switched paths to become a director's assistant, then began making his own films. One summer, while waiting for the funds for a new film to come in, he wrote and drew -- in a single session -- his first graphic novel, which was published in 2015. He then spent three years working on a second graphic novel about the singer Fréhel, which came out in 2018. In 2020, with Dargaud, he published "La Petite dernière" (Little Sister, Europe Comics 2021), which relates the colorful everyday life of star children's author Susie Morgenstern, at the age of ten.