18+ Walkure Romanze: Shoujo Kishi Monogatari

Walkure Romanze's story revolves around Takahiro Mizuno, a student studying at an academy with jousting as its main focus for sport. Takahiro acts as an advisor to the riders of the sport. Takahiro goes through each day tediously until the time of the annual competition draws near. Due to some odd circumstances, his childhood friend Mio Kisaki is enrolled into the competition. As she has never even rode a horse once in her life, Takahiro senses the fear in his friend and becomes Mio's coach.

(Source: MangaHelpers)