  The excited states of Be-12, Be-14 and B-15 have been studied with a method
of antisymmetrized molecular dynamics. In the predicted excited states we find
novel molecule-like structures with very exotic clusters such as 6He+8He in
Be-14 and 6He+9Li in B-15. The origin of the He-6 cluster development in the
very neutron-rich nuclei is understood by the new-type correlation among 4
neutrons and 2 protons. In this paper we also present our recent challenge to
study $sd$-shell nuclei. Shape coexistence problems in Ar-36 and Ca-40 are
discussed.
