In fact, the usefulness of molecular generative models has been criticized by some medicinal chemists, in which they point out even algorithms claiming to attain high-performance scores often generate chemically infeasible molecules, and such molecules are referred to as "crazy structures." In order to find out such inappropriate structures, it is necessary to define and calculate the appropriateness of generated molecules. Some researchers attempt to quantify the appropriateness based on synthetic feasibility by running automatic retrosynthesis tools and counting the number of synthetic steps required to produce the molecule . These approaches can screen millions of generated compounds, but their reliability is not established yet, since automatic retrosynthesis tools sometimes give incorrect synthetic routes for even simple molecules . Given such situations, human-based molecular sanitization is still necessary for ensuring the reliability of molecules generated by computers.