Sugars are being recognized as the third life chain, and many people are now acknowledging their importance. However, compared to the rapid progress and spread of genome science, those of glycoscience are still limited. That being said, it is not that there is no significant progress in glycoscience. We can see remarkable advancements such as the innovation of glycan analysis techniques represented by mass spectrometry, the development of various genetic modification techniques for functional analysis, and the expansion of novel imaging techniques, glycan-related information technology, and databases. So why is glycoscience still lagging far behind genome science? The first reason is the complexity of the glycan structure. Glycans have branches not found in nucleic acids or proteins, and they also have processes called post-glycosylation, such as sulfation, phosphorylation, and epimerization, which further complicate the glycan structure. Therefore, the principles of automatic analysis and synthesis that are effective for nucleic acids and peptides do not apply. Even in analysis by mass spectrometry, there are still challenges in determining detailed structures, such as isomers and linkage diversity. The second reason is that it is difficult to have a uniform understanding of glycan function. Glycans often exist as complex forms of sugars (glycoconjugates), and they have aspects that depend on the physical properties and functions of the proteins and lipids to which they are added. Even if the glycan structure is the same, the role of the glycan changes if the carrier protein changes. Conversely, even if the carrier protein is the same, the function of the protein changes if the glycan structure changes. This versatile nature of glycans sometimes gives an inconvenient impression to life scientists who seek a uniform understanding.