2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/44454Why the charged lepton mass formula m_e +m_μ+m_τ= {2/3} (\sqrt{m_e}+\sqrt{m_μ} +\sqrt{m_τ})^2 is mysterious is reviewed, and guiding principles to solve the mystery are presented. According to the principles, an example of such a mass generation mechanism is proposed, where the origin of the mass spectrum is attributed not to the structure of the Yukawa coupling constants, but to a structure of vacuum expectation values of flavor-triplet scalars under Z_4 \times S_3 symmetries.10 pages, 1 figure, contribution paper to Lepton-Photon 2005High Energy Physics - Phenomenologytext