Sacran is a rare ultrahigh molecular weight polysaccharide with an average molecular weight exceeding ten million g/mol, extracted from Aphanothece sacrum, a cyanobacterium unique to Japan [1]. Chemically, it is an anionic polysaccharide containing many sulfate and carboxyl groups, showing high hydrophilicity and strong interaction with trivalent metal ions. Physically, Sacran demonstrates exceptional water-retention capacity, approximately five to ten times greater than that of hyaluronic acid. Also, Sacran exhibits liquid crystallinity and forms various fibrous and gel-like structures through self-organization. Taking advantage of these characteristics, many skincare products providing moisturizing effects and barrier functions are commercially available. Furthermore, hybrid fibers incorporating Sacran’s hydrating properties, particularly when blended with rayon, have led to the development of novel functional textiles. In addition, Sacran is attracting attention in the medical field, and therapeutic effects on skin diseases such as atopic dermatitis and anal fistula have been confirmed [2, 3].