The horse who can write a paragraph gets to be a chess piece. Only the most erudite of horses gets selected to be a chess piece. The knight’s chess piece is represented by a horse, and for a horse to earn this honor, they must first write a paragraph explaining why they deserve the honor.
Upon being told that he will never be a chess piece, the horse slips into a coma (こま). The horse will never awaken from this coma as he knows he will never fulfill his dream of becoming a chess piece, so he has nothing to live for.