Tenjo Night is a cybernetic doll custom ordered by Riiko. As such, he is the "perfect boyfriend": charming, dependable, intelligent, athletic, good-looking, sensitive, and completely devoted. At first he is perfect for Riiko because it is in his programming, however as the series progresses, Night develops true emotions and a genuine love for her. He is 6' tall as shown on the back of the first volume of the English version.
an extended description!