The progress of optical science has been led by the new lasers. One of the innovative lasers is optical frequency combs invented in 2000, which receives the Novel Prize in 2005. The optical frequency combs have provided various applications such as ‘ultra-’precise spectroscopy, ‘ultra-’precise distance measurement, and ‘ultra-’low phase noise microwave generation. Nevertheless, it is unexpected that current optical frequency combs will be installed in the real world due to the large size and high price. To overcome the drawback of optical frequency combs, chip-scale optical frequency combs (called microcombs) have been attracting significant attention. In addition to the potential to be chip-scale and mass-productive, I am interested in the unique feature of microcombs. I will develop new applications of microcombs, which utilize the unique feature, such as ‘ultra-’broadband RF equipment, ‘ultra-’fast and ‘ultra-’large-capacity wireless/optical communication, and ‘ultra-’fast and ‘ultra-’power-efficient neural network, which will be installed in the real world.