  The charged lepton mass relation $K \equiv (m_e +m_\mu+m_\tau)/(\sqrt{m_e}
%+\sqrt{m_\mu} +\sqrt{m_\tau})^2= 2/3 $
  is excellently satisfied by observed masses (pole masses). However, the
formula $K=2/3$ should be never satisfied with the observed charged lepton
masses. We will review a mechanism by proposed by Sumino and recent related
topics.
