Analysis of the PubchemQC database shows that it is not trivial to discover favorable fluorophores with desired properties (Figure ). Favorable fluorophores are required to have high oscillator strength, which may lead to a strong emission spectrum, and diverse emission colors. About a half of PubChemQC molecules have the maximum oscillator strength less of than 0.1 (Figure ). Only 4.12 and 0.18 percent of molecules have oscillator strength over 0.5 and 1.0, respectively. In terms of excitation energy, most molecules have their maximum intensity absorption in the ultraviolet region (Figure ). Only 0.4 percent of molecules in the database have their absorption peak in the visible region. Taken together, the number of molecules whose maximum intensity absorption in the visible range and oscillator strength over 0.5 is only 880, corresponding to 0.03% of the dataset. This result demonstrates that highly accurate electronic property prediction methods are essential for designing a novel fluorophore efficiently.