My research area is number theory. More precisely, I am interested in mysterious relations between L-functions and Selmer groups which are attached to algebraic varieties defined over the rationals. One of the difficult and interesting points is that L-functions are analytic objects but Selmer groups are algebraic. So far, I have studied relations between L-functions and Selmer groups of elliptic curves and elliptic modular forms by p-adic methods, where p is a rational prime number. I will next study to understand higher-dimensional objects as well.