Asari was born in the Shimotsuke province of Japan in the year 1166 as Tetsuya Nakamura. He spent the twenty years of his mortal life as a wanderer with his family, who were merchants in the region. However, his open-mindedness and sense of justice caught the eye of a kitsune, and at the age of twenty, he underwent the Kaiden Giten ceremony, trading his mortal life for that of a kitsune.
Asari spends most of his time working on various forms of technology, as his inquisitive, quick-to-learn nature lends well to constant accumulation of knowledge. Some of that knowledge is undoubtedly useless, but is still something that he takes pride in. He has something of a short temper; he is quick to anger and just as quick to act accordingly.