Rin Kujou

Rin Kujou 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. Rin is generally expressionless and formal but can get really angry when it comes to Rito's clumsiness towards her, Aya, and most of all, Saki, whom she is very loyal to. Although she has shown to smile practically once to Rito as a sign of understanding, it didn't last long due to another one of his mishaps. Source: To Love-Ru Wikia