The use of topological invariants for the characterization of material phases has been quite successful. Non-trivial topology is reflected by physical observables near the boundaries of systems as a bulk-edge correspondence. Recent surprise is that the idea is applicable to non-quantum systems such as photonic crystals, geophysical equational flow near the equator of the earth. Even more than that such as sociological phenomena governed by the game theory. Since restriction of the unitality is absent in classical description, a natural extension of the topological phases is a non-Hermitian system. Then it can be natural to discuss non-Hermitian topology in game theory published in our recent paper, “Non‑Hermitian topology in rock–paper–scissors games” by Tsuneya Yoshida, Tomonari Mizoguchi & Yasuhiro Hatsugai, Scientific Reports, 12:560 (2022) (open access).