Janko was a regular contributor to the magazine Fillette, for which he created many exotic and fantastic strip in an Art Nouveau style. His stories include 'Edith, La Rose du Val d'Argent' (1917), 'Paola, la Vénitienne aux Cheveux d'Or', 'La Filleule des Farfadets' and 'Ginette'.
He also made historical strips like 'Bernard le Ménestrel' (1920) and 'La Page de Dame Isabeau' (1921). In addition to Fillette, he was present in L'Epatant with 'Guh-Gluce-Glip' and 'Les Compagnons de la Nuit' and in Lili with 'Le Paradis des Fées' and the cover story 'Les Sept Enchantements du Prince Cassib'.
