This paper revisits multiplicative bias correction for some asymmetric kernel density estimators (KDEs) when the data is supported on [0, ∞) d or [0, 1] d. The original method was introduced by Jones et al. (1995) for the standard KDE with symmetric kernel. After Hirukawa (2010) for beta KDE, there have been renewed interests for applications to the asymmetric KDEs. We stress that the variance manipulation must be performed by looking at four terms from the law of total variance/covariance, in which only one term is negligible, while other three terms contribute to the variance formula. It turns out that, even for recently developed asymmetric KDEs, the achievement of the reduced bias is available, at the expense of the constant-factor inflation of the variance. Interestingly, the same factor appears in other bias correction methods.