At the beginning of the Heian Period, Mikkyo, Esoteric Buddhism, was brought to Japan and many 'Mikkyo-zuzo paintings' in Sumi, were produced in order to correctly pass down complicated forms such as a Buddha statue, Buddhist alter accessories, and Mandala, etc.
平安時代初期、密教の伝来とともに、仏像、仏具、曼荼羅等の複雑な形態を正しく伝承するために、墨一色で線描された「密教図像」が多数制作された。