Occurrence frequency distribution of superflares as a function of flare energy.(a) Bold solid and dashed histograms represent the occurrence frequency of superflares on all G-type main sequence stars detected from short- (this work) and long-cadence data (Shibayama et al. 2013) as a function of total energy of superflares, respectively. The vertical axis indicates the number of superflares per star, per year, and per unit energy. Error bars represent 1−σ uncertainty in the frequency estimated from the square root of the number of detected flares in each energy bin and the uncertainty in flare energy. (b) Same as (a), but for the corrected frequency distribution from the short-cadence data which was calculated so that the ratio of total observation time in short-cadence mode is the same as that in long-cadence mode (see text for details of the correction).