Kujō Rin

Rin is Saki Tenjouin's loyal and longest known friend. Rin is skilled in kendo and has been a loyal bodyguard to Saki for years, as her family has always served the Tenjouin family in this position. The bespectacled Aya Fujisaki is weak-willed and became associated with Saki after she and Rin protected her from bullies when they were children.

While Rin is very loyal and caring to Saki, she is also very dutiful. These made her conflicted when Saki once ran away from home, and Rin was ordered to bring her back, even by force. But after Saki managed to settle things with her family, she and Rin were able to remain friends.

Rin is usually calm and very composed, and is perhaps the most mature character in the series, at least among the students, despite how few moments her character was explored without being together with her friends. Like Saki and most other girls, she is also not completely safe from the antics that surround Rito Yuuki, and naturally, she has a negative impression of him, but she has shown few instances of potential to understand him better and perhaps grow more patient with him.

Throughout most of the series, Rin is hardly ever seen without accompanying Saki Tenjouin and/or Aya Fujisaki, and has interacted personally with very few other characters in the series. However, in To LOVE-Ru Darkness, she has caught the notice of Momo, who is considering adding her to the Harem Plan, hoping that Rin would open up to consider Rito as a love interest.

Appearance
Rin has brown eyes  and   hair, to which she has a pony tail with a blue scrunchie. Rin is often seen with a motionless face.

Personality
Rin is seemingly expressionless and formal but can get really angry when it comes to Rito's clumsiness, although she has show to smile pratically once in the whole series to him and only him as a sign of understanding, but it didn't last long due to another one of his mishap, she think of his sister is more reliale than he is. However, Rin may have develop feelings towards Rito in Darkness Chapter 33 and seems to blush around him. She shows her most loyalty to Saki and her family.

History
Rin has served Saki as her body guard but saki has always thought of her as a close friend insted. They first met when Rin came to saki in the garden introducing herself as the daughter of her families butler and the tells her that she will serving her starting from that day. Saki acted friendly towards Rin who was deeply touched by it.

Powers and Abilities
Rin is known to practice Kendo, and is often seen carrying a shinai. The only times she is seen using kendo are either when training or when she's mad at Rito whenever his clumsiness results in him groping her, Saki or Aya. She has also beaten up the principal time from time.

Because she does not involve herself with Rito, his alien friends, or their adventures and antics, she is mostly left out of any potentially dangerous situation, and so the full extent of her expertise in Kendo have not yet been seen.

Saki Tenjouin
Rin is Saki's bodyguard and the oldest and closest friend she has. Her family has served the Tenjouin family for generations. Rin shows great loyalty to Saki and gladly accepts any request she gives her regardless of what it is. Rin has deep desire to protect Saki from any danger.

Saki considers both her and Aya to be her closest friends, to the point that Saki ran away from home rather than be forced by her father to study abroad without her friends. Rin, on the other hand, while caring for and greatly respecting her, is a little more divided between her loyalty to her Saki-sama and obedience to her family, who serve Saki's family. This was seen when Saki ran away from home, and Rin arrived to bring her back by force rather than support her. Ultimately, Saki did not leave to study abroad, and they were able to remain together.

Saki noticed Rin's blushed facial expresion towards Rito and claims it might be love, she say's that she will support her even if it is him.

Ayako "Aya" Fujisaki
Even though Rin and Aya are always seen together with Saki and they both admire her, they don't exactly have any other thing in common and Aya shows more admiration to Saki than Rin does, as Rin often shows less emotion.

They first met each other when Saki and Rin saw Aya being bullied by a group of boys, and Saki insisted on helping her, while Rin just followed her. Since then, Aya has always followed them.

It's not quite known how Rin and Aya feel towards each other. They are friends to each other, but more often follow and pay attention to Saki, and have not often been seen interacting directly to each other.

Rito Yuuki
Rin dislikes Rito's perverted clumsiness, especially around her, Aya and most of all Saki, and doesn't hesitate to hit him for it with her wooden sword (sometimes with a real sword, and on one occasion, she used a gun on him). One time, she and Aya requested, or rather forced, Rito to arrange a meeting between Saki and Zastin, and when he helped them, Rin has shown a slightly better understanding towards him (even willingly smiled at him), but unfortunately, that did not last long before Rito's clumsiness struck again, ending her short-lived respect for him. One time, when Rito was turned into a mouse because of Lala's invention, Rin spotted him and thought he was cute (unaware that it was Rito).

She has shown kindness and hospitality to Mikan, and finds the younger sister to be a lot more reliable than her brother. In To Love-Ru Darkness Chapter 31, she asks Mikan to help work in the Tenjouin mansion, but Mikan instead requests that she accepted Rito in her place, persuading her that he can be counted on when someone is in trouble. Unfortunately, Rito's clumsiness persists to harass her and Saki, despite his best intentions. Rin feels that she's just unable to think of him the way Mikan does, until he saved her the sword bladix's control and starts to blush around him (To Love-Ru Darkness Chapter 33).