One of the unique and interesting aspects of hypernuclei is structure change due to the addition of a Lambda particle as an impurity. Since a Lambda particle is unaffected by the nuclear Pauli principle in hypernuclei, it can penetrate into nuclear interior and modify nuclear structure through the interactions between the Lambda and nucleons. For example, in $^7_\Lambda$Li, the inter-cluster distance between the alpha and deuteron clusters of the core nucleus $^6$Li is reduced by the addition of a Lambda particle, which has been confirmed by observing the E2 transition probability.
In the heavier Lambda hypernuclei, we can expect that many kinds of phenomena will occur by the coupling of a Lambda particle to the ordinary nuclei, because they have various structures such as pronounced cluster structure, triaxial deformation and coexistence of cluster structure and/or deformed mean-field-like structure in the ground and low-lying states. As examples, in this talk, we will focus on several phenomena expected in the Lambda hypernuclei: 1) “dynamical changes of nuclear structure”, 2) “dependence/sensitivity of the Lambda binding energy on nuclear structure” and 3) “coupling of Lambda to deformed core nuclei”. Furthermore, we will also discuss the importance of the hypernuclear experiments at JLab on the hypernuclear structure study.