Pyrochlore antiferromagnets are a typical example of frustrated magnets in three dimensions. I studied the S=1/2 Heisenberg model on this lattice and found a dimer/tetramer order with a hierarchical structure. I used an approach that the spin exchange J’ connecting tetrahedron building blocks varies from the intra-block coupling J and the ratio J’/J was a “small” control parameter in my theory. Okamoto et al. in Hiroi group reported a material with this exchange pattern realized, and that is an S=3/2 antiferromagnet Li(Ga,In)Cr₄O₈ named breathing pyrochlores [PRL 110, 097203, 2013]. In the end member LiInCr₄O₈, the ratio J’/J is small and a magnetic order appears with lowering temperature preceded by a structure transition. I have generalized my previous theory and applied to the S=3/2 case, and discuss this transition.