Human-Residential Bifidobacteria (HRB) are Bifidobacterium adapted to the human gut, characterized by resistance to lysozyme and distinctive metabolic profiles. HRB plays a meaningful role in the gut microbiome. The gut ecosystem functions as a “microbial relay,” where bacteria act sequentially to generate key metabolites such as short-chain fatty acids (SCFAs). Our basic and human clinical research demonstrates that HRB strains serve as key contributors within this relay system. We will also introduce our newly developed HRB logo representing this concept.