The He + Li and He + Li reactions have been studied using a 18 MeV He radioactive beam and a highly efficient and segmented detector set-up. Triple coincidence events corresponding to the He + Li → He + α + d, He + Li → 2α + t + n and He + Li → He + α + t reactions have been clearly observed. The dominant mechanism of these reactions has been found to be a sequential decay through the known cluster states in Li, Li, Be, Be and Be. In particular, the sequential α-decay of the Be state at E = 7.54 MeV has been observed although its decay energy is much smaller (130 keV) than the decay energy for neutron emission (730 keV). Furthermore, the Be state at E ≈ 10.2 MeV has been found to be strongly populated in the reactions with both used targets. Angular correlations analysis of the events corresponding to the 10.2 MeV state α-decay suggests the 4 assignment. Both of these observations indicate a special, well-developed He + α cluster structure of the Be states involved. The structure of several low-lying Be states is also discussed.