“Meant to ward off evil spirits, modern komainu statues are almost identical, but one has the mouth open, the other closed. This is a very common characteristic in religious statue pairs at both temples and shrines. This pattern is however Buddhist in origin and has a symbolic meaning. The open mouth is pronouncing the first letter of the Sanskrit alphabet, which is pronounced “a”, while the closed one is uttering the last letter, which is pronounced “um”, to represent the beginning and the end of all things. Together they form the sound Aum, a syllable sacred in several religions like Hinduism, Buddhism, and Jainism.” Wikipedia article.