Several studies have investigated efficient algorithms to detect highly correlated itemset pairs. However, we regard itemset pairs with even medium degree of correlations in a target database, provided the correlations are drastically higher than the corresponding ones in another databases to be contrasted. We consider that the greater change of correlation can be evidence that something to be remarked occurs implicitly in the target database. In a problem of finding such itemset pairs, we consider the problem in a case where one component is given by users. For the given component, we try to find the other component. Because of the nonmonotonicy of degrees of correlation chage, the problem of finding the other component is difficult. However, we prove some monotonicity if we consider some itemsets in the process of mining the other component.