In nature, many carbohydrates exist as glycosyl compounds (glycosides); they include oligosaccharides, polysaccharides, glycolipids, glycoproteins, and nucleosides. These compounds are biosynthesized by the action of synthetic enzymes (synthases), hydrolyzed by glycoside hydrolases (glycosidases), and ultimately converted to small molecules such as carbon dioxide and water [1]. In other words, two types of carbohydrate-related enzymes with different properties are greatly involved in the earth’s carbon cycle. The proposed “Glyco-Chemistry Cycle System” is the first manufacturing system that uses only inexpensive and readily available glycosidases to construct a functional polysaccharide/oligosaccharide library and is a new concept that serves as the foundation for creating next-generation innovations with low environmental impact, economic efficiency, and diversity (Fig. 152.1) [2–4]. The applied research based on this concept that involves the aqueous direct anomeric activation of unprotected sugars [5] and the design of low-activity endo-β-N-acetylglucosaminidase catalysts, especially the development of antibodies with uniform glycans and antibody-drug conjugates (ADCs), has made significant progress since around 2018.