Sonora comes from an idea to connect the inside and outside of a letter. When drawing a letter digitally, the counter-space inside and the outline of the letter are drawn separately and have opposing contour directions, inevitably influencing each other to create a shape. This contrast and rhythm in letter shapes are present in a single line. The name comes from a track in A Letter from Slowboat, the 2015 album by Ryo Fukui, which Heejae Yang listened to while drawing the typeface.