The following is the story and background for the renowned twin brothers Sen and So Yukatori.

Sen is known as "The White". This is due to his dedication, commitment, and general good nature. Sen has black hair and is always seen dressed in white.

So is known as "The Black". He is generally manipulative, conniving, and has a poor disposition. So has white hair and is always seen dressed in black.

Sen showed promise in the martial arts at an early age and was soon accepted at a prestigious school. Sen has remarkable dedication and unending devotion to continued learning and development in the arts. Sen excelled in his studies and graduated with honors.

So was not idle during his bother's training. He practiced in dark circles and in dark arts.

After returning home from school, So challenged Sen to a duel. So felt he was disrespected in the family and wanted to prove that he was greater than his brother. Sen would not agree to his brother's challenge and warned So of his advanced training. So still would not relent and eventually Sen agreed to fight, only to appease his twin.

Sen started the fight with a few simple moves and was surprised to find his brother indeed had skill in the martial arts. Sen continued with more advanced moves and soon found So was his equal. Sen realized, to his utter amazement, that even his best attacks were matched by So. The fight continued for many hours, neither gaining ground on the other until both were exhausted. Their respect for each other was never questioned again.

The twins gained fame as they continued to win team tournament after team tournament. They won the team champions title their first year. For the next 2 years they continued to win and earned great sums of money as a result. Soon they adopted the Sen So symbol (an adaptation of the yin-yang) and started an arena and school in their local town.

The Sen So arena adopted new rules on combat that required equal opportunities for weapon selections and styles of fighting. But the key change was the elimination of the "surrender or die rules". All matches would be based on points scored and would end based on time limit or maximum points. These were done at Sen's insistence.

The result was that the Sen So arena had greater participants who stayed healthier and fought more often making it the largest tournament around. The Sen So arena offered large prizes and grew to be one of the most popular in the land.

Sen and So are still feared and undefeated in team combat.

It has been said to be both amusing and exhilarating to see the two twins in combat against one another. This rarely happens beyond the annual school Shuhan competition. It is often referred to as the "Dance of Mirrors" where it is said that the real skill lies with Sen, but the real power lies with So