Hikaru had often dreamed of things he didn't understand. In these dreams, he was looking from the eyes of another. He figured it was a man which these eyes belong to, later on as the visions continued to his childhood and preteen years.
He found that the man was living in the times of old Japan. Later he researched, in the Heian period.
There was one thing that dominated each and every dream he had. The man always was playing a game, a game Hikaru later knew as 'IGo'.
The man played it morning after his little hygienic routine. He played during meals, morning, noon then night. There was never a day that he had not touched a stone to place upon the board. No dream had consists much of anything else.
Even the dream of which the man died was filled with the game; a game of which he was disgraced at in front of his liege. Of where he had lost as his mind was riddled with distraught of such a dishonor.
The man had lived for Go. He had loved it as much as his life so much so that when the right for him to play was taken away, he had not seen much reason to live.
Death was the only comfort he could find.
Hikaru pondered upon the man's memories. Through the confusion the memory brought him as a child to the sympathy he felt as an almost teen till the day Hikaru somehow shared the pain and anguish of the man and felt them as his own. He felt then that he knew this man, this man called Sai.
Somehow his young mind just knew that this man was him a millennia ago.