Rin was a sweet and friendly girl who cared deeply for her comrades as well as her village. She often played the role of peacemaker during Obito and Kakashi's many spats while remaining objective. Rin was also an intellectual individual, witnessed by her ability to learn as well as use high-level medical ninjutsu at such a young age.

She proved to be perceptive under stress as seen in when she thought Obito had died and after being captured by the Kiri shinobi, she concluded that she should not return to Konoha or the village would be attacked. Rin was a devoted person as seen in her unwillingness to abandon Obito even when her own life was in great peril. She had a very strong will, as even though under what seemed to be the harshest of genjutsu, she would not break. While Obito had romantic feelings for her, Rin did not share them, instead having romantic feelings for Kakashi which were revealed only shortly after Obito was incapacitated during the cave in.

Rin spent her young childhood playing alongside her best friend Obito Uchiha, often cheering him on when he struggled. On the day of their entrance into the Academy, Rin was present when Obito arrived after the ceremony had ended, which left him dismayed. Rin, however, handed Obito his entrance documents, which he was very thankful for. Rin was also the first to congratulate Kakashi Hatake after he'd graduated from the Academy a year ahead of the rest of his class — Kakashi having gotten his own forehead protector after successfully performing the Clone Technique. After graduating from the Academy a few years later, Rin was placed under the jōnin tutelage of Minato Namikaze, alongside Obito and Kakashi. In the anime, for their final test to become genin, Minato tasked his potential students with taking one of two bells from him in actual combat. While initially, the team attacked Minato independently, easily being outmanoeuvred by the veteran ninja, Kakashi convinced Rin and Obito to work with him, ultimately earning Minato's approval to become his students as they passed the real test: showing teamwork.

When Minato's students partook in the Chūnin Exams, Rin and Kakashi stood outside the gates of the Forest of Death waiting on the chronically late Obito to arrive. While in the forest, they were confronted by Might Guy, Genma Shiranui, and Ebisu. Before they could attack as a team, though, Rin was shocked to see Obito move to attack, but before Obito could do anything, he was knocked down by Guy. She later dressed Obito's wounds as Obito professed his pride in his clan, and his dream to be Hokage. She later watched with bated anticipation and cheered as Kakashi fought Guy during the third round of the exams with Kakashi defeating Guy. After Kakashi became a jōnin, Rin would concoct a top-secret celebration for him much to Obito's dismay due to the fact that Obito had hoped to use the moment to presumably tell Rin that he loved her.

Rin was a young girl of average height. She had straight brown hair, which was cut in a chin-length bob that framed her face, and brown eyes. When she was a child in the Academy, her hair was long, hanging to nearly the top of her shoulders. She also had a rectangular purple marking on either sides of her cheeks. She wore a long-sleeved black top and a light purple apron-skirt, under which she wore black shorts. She also wore the standard Konoha forehead protector, along with a pair of sandals, red stockings that stopped at her thighs, and a small, red bracelet on her left wrist although it should be noted in addition to the bracelet being visible in the anime, it is also visible in a few pages of the Naruto manga. While on missions, Rin carried around a backpack instead of a pouch containing all of her equipment.

As an Academy student, she wore a simple outfit consisting of a light-coloured blouse with a bow tied in the middle and a simple, sleeveless haori.[14] As a genin, Rin wore a light purple outfit with shuriken patterns over it, with a belt around her waist and several pouches. Underneath this, she wore chain-mail armour, and calf-length sandals.