Yuri Kagi: Senpai no Himitsu wo Nozoitemita

On her first day of work, Asou is assigned the cold and demeaning Mochizuki as her sempai. At first, Mochizuki treats her horribly, making her run errands and take care of her pets, until the day comes when Asou accidentally observes a different side to her senior. (Source: Amazon, translated)