Saiyu grew up in the tranquil Federation of Windurst. He was brought up by one elderly grandmother, who told her young grandson fantastic stories about archery and the War between the people of Vana’diel and the Shadow Lord’s armies. When Saiyu’s grandmother died during his early adolescence, Saiyu was effectively cut loose from all family ties.

He was good at picking pockets and lifting latched doors simply because of his graceful agility and nimbleness. However, Saiyu intensely disliked the stigma that being a thief seemed to bring on, and by the time he hit adolescence, he was struggling not to indulge in that particular sin. He was not over fond of work either, but preferred to explore the vast hills and waterways surrounding Windurst. Because of this, he gained the reputation among some of being a shiftless, good for nothing slacker. Saiyu had early conceived a grim dislike for authority figures and those wrapped in their own narrow views, so this reputation didn't unduly upset her. It simply added fuel to his resolve to leave this tired little town.

The idea of lost treasures fascinated him. They combined his interests in exploration and money. He began to search for old relics around Windurst and the outlying lands out of curiosity, boredom, and hope. He was naturally somewhat of a loner, and wandering around the country suited him just fine. Besides, there was always the chance that he could find something of value and skip out of Windurst with wealth and fame. So he silently roamed, searching for pieces of history by himself.

That is, until he met Nina.

To the young Elvaan desperate to escape his life, Nina was a breath of fresh air, a momentary reprieve from his struggle. Nina was beautiful, intelligent and, most importantly, she shared Saiyu's enthusiasm for the new and undiscovered. To Nina, Saiyu must have represented excitement, adventure, and an escape from her dominating father.

As they began spending more and more time in each other's company, Saiyu began to look for new ways to impress his love. One day, he stumbled across knowledge of buried treasure in the low mountainous region nearby and decided to take Nina with him to search for the treasure.

Unfortunately, the rope bridges used to cross the ravines in the area were none too sturdy. Nearing his goal, Saiyu threw caution to the wind and started running across them. He was heedless of his danger when one of the ropes began to break as he was almost across one of the longer bridges in the area. He might have slipped to his death had not the more conscious Nina shoved him out of harms way and onto the ledge a few feet away. Saiyu immediately spun around and reached out a hand to catch her and pull her to safety. And although he was able to hold it for a brief instant, her arm slid out of his hand. She was the one who fell.

Through some miracle, her wounds weren't fatal. The fall had damaged areas of her mind and she could no longer remember Saiyu at all. A horrified Saiyu struggled to convince her that yes, they had really known one another just hours before. He pleaded with her to remember until her father tried to kick him out of the house in a furious rage saying how much grief he was bringing on his daughter. The final, crushing blow came when Nina asked him to go away because he upset her father so.

Saiyu turned his back on Windurst, not to come back until much later and under quite different circumstances. His soul bitter, he wandered for a bit, traveling the wide world. After a while, the piercing memories of Nina and her rejection faded and he was able to laugh again. He was naturally cheerful and witty, and the bitterness of the memories of just a short while ago did not show through. It startled him to realize that people liked him solely on that value, that away from Windurst he was no longer judged by his past. However, the memory of Nina would always be with him and moods of depression would sometimes seize him.

He tried to put the past behind him, and for a while she succeeded. He fashioned himself as a treasure-hunter, an explorer who searched the entire world for forgotten relics. While some might attempt to argue that this was basically thievery, Saiyu was quick to argue about the merits of his trade and skills. For a time he was content in his new lifestyle.

Perhaps inevitably, it was Nina who pulled him low again. Saiyu was horrified to learn that the Shadow Lord’s armies had attacked Windurst. He soon discovered that his worst fear, his darkest dream had come to pass. Nina was dead. As if to twist the knife deeper into the depths of his heart, he was informed that in the end she had remembered him and the life they had lived together. In the end, Nina had called out to him and he hadn't been there.

This revelation nearly sent Saiyu over the edge. He suffered sever bouts of depression and anger. But after a period of intense drinking and contemplation of suicide, he pulled his grief inside of him and locked it away. The new man that emerged was certainly grimmer than the Saiyu that people once knew. His anger was turned into determination and drove him to inflict as much pain on the Shadow Lord and his minions, to bring that encroaching monstrosity and all his followers down for the pain he had caused him.

It was probably fortunate that Saiyu encountered the Shadow Dragons before he made a lone suicide mission against Castle Zvahl. The Shadow Dragons were an elite group of mercenaries desiring an end to the Shadow Lord's advances and a return to the peaceful world they once had known. Their ranks were small, but they had two important assets: the extremely capable Tyreal and the willing assistance of the young Dragon Knight Ryuuza.

Saiyu was another advantage to the Shadow Dragons as he was deftly capable of espionage and other activities of a delicate nature. Because he was often used to maintain the contact between Ryuuza and the Shadow Dragons citadel, he grew to know Ryuuza on an intimate level. The rather lecherous knight’s true personality was slowly revealed to the young man, and the initially repulsed Saiyu began to actually view the Dragoon as a friend.