This volume consists of one expository paper and two research papers: T Hirai, A Hora and E Hirai, Introductory expositions on projective representations of groups (referred as E])T Hirai, E Hirai and A Hora, Projective representations and spin characters of complex reflection groups G(m,p,n) and G(m,p,∞), I;T Hirai, A Hora and E Hirai, Projective representations and spin characters of complex reflection groups G(m,p,n) and G(m,p,∞), II, Case of generalized symmetric groups.Since Schur's trilogy on...