Recently, most diagrams which directly communicate mathematical principles and structures are made with established methods. As a whole, their emphasis has shifted to communications appealing only to sensibilities. While there is a tendency to too often make light of their essence, they represent the origin of visual design. Tetsuya Ota put his heart into this conservative area. He visually represented changes based on corporate data and social phenomena and achieved a high level in graphic design. He is very important as one doing the work of an actual designer. Mitsuo Katsui