[en] Recent experimental work on the 1/8 problem by the group is reviewed not only in the La-based cuprate but also in the Bi- and Y-based ones. In the partially Zn-substituted Bi₂Sr₂Ca_1-xY_x(Cu_1-yZn_y)₂O_8+δ, the authors have found anomalous suppression of superconductivity at x = 0.30--0.35, where the hole concentration per Cu p approximately 1/8. Moreover, it has been revealed from the μSR measurements that the Cu-spin fluctuations exhibit slowing-down behavior at low temperatures in these samples. These results are suggestive of the stripe correlations of holes and spins tending to be pinned by Zn at p approximately 1/8 in the Bi-based cuprate as well as in the La-based cuprate. In Y_1-xCa_xBa₂Cu₃O_7-δ, the 60 K plateau of Tc has been found not to be correlated with the oxygen content but to be interpreted as being due to the suppression of superconductivity at p approximately 1/8. Accordingly, they conclude that the 1/8 problem is common to all high-Tc cuprates with the CuO₂ plane. Moreover, they have found transport and Tc anomalies around x = 0.22 in La_2-xSr_xCu_1-yM_yO₄ (M = Zn, Ga), suggesting a possibility that an order of holes and/or spins is formed or fluctuates in these samples in the overdoped region