I have studied mainly five interesting subjects in about 50 years from 1961 to the present; these are [I] Gamow-Teller giant resonances with isobaric analog states (1961 - 1967), [II] cluster structure in nuclei (1965 - 1980), [III] hypernuclei (1980 - 1995), [IV] unstable nuclei (1987 - present), and [V] roles of pion (tensor force) in nuclei (2001 - present). The intension of these studies and their key points are summarized briefly
