In order to discard unwanted molecules, various quality filters have been proposed. For example, Pan Assay Interference Compounds (PAINS), and medicinal chemistry filters (MCF) are implemented in MOSES packages . Although these filters are useful to some extent, some unwanted molecules remain unfiltered because which substructures are unwanted depends on each user's individual situation. Therefore, users must prepare their own custom-defined filters to get meaningful generated molecules. In fact, REINVENT , one of the most cited and widely used generative models, provides Custom Alerts (CA) component, which enables users to define their own unwanted substructures. Actual preparation of custom filters is a laborious task, and tools for supporting visual inspection of users are essential to check and find out unwanted molecules/substructures among generated molecules.