Rin Tohsaka is one of the three main heroines of Fate/stay night who acts as the Master of Archer in the Fifth Holy Grail War. Rin Tohsaka is the heroine of the Unlimited Blade Works route in Fate/stay night.
Two centuries ago, the Rin Tohsaka House, in collaboration with the estates of Makiri and Einzbern, helped found the Fuyuki Holy Grail Wars. The land of Fuyuki City, which possessed the second greatest spiritual power in all Japan, was owned by Rin Tohsaka 's ancestor, Nagato Tohsaka; at the behest of the Einzberns, he provided his property as battleground for present and future wars. Nagato was a kirishitan, as well as a pupil of Zelretch; these titles gave him considerable influence in both the Mage's Association and the Church, allowing the Rin Tohsaka family to participate in the Holy Grail Wars, free from harassment by either organization.

Rin Tohsaka was brought up as the successor to her family's magecraft, Rin Tohsaka was instructed by her father to prioritize magecraft over her own interests. Ten years ago, Tokiomi Tohsaka was selected as a Master in the 4th Holy Grail War, and Rin Tohsaka was entrusted to take care of the Tohsaka estate until his return. Rin Tohsaka mother, Aoi Tohsaka, was left in a debilitated state from the war, so Rin Tohsaka care was left to her guardian, Kirei Kotomine. After Rin Tohsaka father was killed, Rin Tohsaka continued to improve her sorcery with some guidance from Kirei Kotomine. Rin Tohsaka also had a maid working since back when Rin Tohsaka father was alive, but left when Rin Tohsaka entered middle school, leaving her uniform behind. To divert attention from Rin Tohsaka private life, Rin has diligently strived to earn the admiration of her peers, even though Rin Tohsaka is secretly stingy, tomboyish, and a perfectionist. The rights to the Tohsaka lands were inherited by Aoi after Tokiomi's death, and subsequently inherited by Rin Tohsaka after Aoi's death. Kirei managed them as Rin Tohsaka 's guardian, and because of his foolhardy and coarse management, the majority of profitable properties ended up in the hands of others. It is possible that he believed the wealth was bad for her upbringing due to following the principles of humility and poverty.

Although Rin Tohsaka resents the sacrifices she has endured for the sake of tradition, Rin Tohsaka is fiercely competitive and eager to prove herself as a skilled and capable magus. Rin Tohsaka was immensely disappointed at summoning Archer and ended up in a quarrel with him; however, the duo soon reconciled, set aside their differences and quickly got along.
Rin Tohsaka is a young woman with aqua eyes and long wavy brown hair in a two-side-up hairstyle, which consists of part of Rin Tohsaka being made into twin tails tied with black ribbons, while the majority hangs loose. During school, Rin Tohsaka wears the standard Homurahara uniform, which Rin Tohsaka sometimes accompanies with a long red coat. Rin Tohsaka casual clothing consists of a red turtleneck, a black skirt and long black socks under brown leather flats.

When Rin Tohsaka was young, Rin Tohsaka clothing consisted of a white shirt with a red necktie, a red skirt and long black socks, much like when Rin Tohsaka becomes older. In the fifth Holy Grail War, Rin Tohsaka prepared a plain skirt and shirt for Saber, though it was originally a birthday present from Kirei.

As an adult, she put down her hair. Two years after the Heaven's Feel route ending, she wears a long sleeve red shirt and a long maroon skirt. Her alternative costume is a long red jacket, a white polo neck jumper, a black mini skirt and long leather boots.