The author, Dr. Fumihiko Suekane, is a professor of Research Center for Neutrino Science, Tohoku University, Japan. He is an elementary particle physicist. He contributed to the discovery of the reactor neutrino oscillation as a core member of the KamLAND experiment. He was awarded the Koshiba prize and Breakthrough group prize for the achievement. Recently he suceeded to measure the last neutrino mixing angle Theta-13 He is also interested in teaching intuitive and concrete particle physics and have written some text books. He won Blaise Pascal Chairs (BPC) by Promotion of Neutrino Science and was invited as a guest researcher at Laboratoire AstroParticule & Cosmologie, Paris, in 2017- 2018. This book is an outcome of his activities as BPC while he was staying at APC lab.