It is Ayu's birthday, and Soichiro (a clothing designer who supposedly died 12 days before the beginning of the story, and was "revived" as a bird, and now can predict when he'll die again) made him an entire outfit.
Ai no Kusabi takes place on the world of Amoi, ruled over by a computer named Jupiter. Jupiter has installed a number of strict social rules to its society. Among other things, social status is determined by hair color.
The Shogunate is in its final years, and war is fast approaching. When Akizuki Yojiro, a dark and mysterious mercenary, nears something supernatural with some kind of importance to him, the ornament on the end of his sword hilt waves in its direction, his eyes glow mysteriously, and he is driven to go after it.