Based on Ekaterina Kurae's chapter 16 from the manga, and episode 10.5 of the anime.

Short spin-off episodes included in Blu-ray/DVD volumes of the main series.

Learning to ride and tame dragons comes easy to most students at Ansarivan Dragonar Academy—except for first-year student Ash Blake, who is known by his fellow classmates as the number one problem child. Poor Ash is the laughing stock at school because, despite his unfashionably large star-shaped brand that marks him as a future dragon master, he has nothing to show for it. His dragon has never appeared. Until now, that is. One fateful day, Ash's dragon awakes in full glory, but appears different than any dragon ever seen before—in the form of a beautiful girl! What's worse, Ash soon discovers that this new dragon has attitude to spare, as she promptly informs him that she is the master, and he, the servant. Ash's problems with dragon riding have only just begun. (Source: ANN)

For high school students like Shouichi Kamita, university entrance exams and the future are common concerns. It is also during this time in life that a mysterious emotion that vexes people of all ages may begin to weigh upon one's mind—love. At this point in his teenage years, Shouichi finds three girls he could see himself having a future with: the ever-cheerful Hikari Tsuneki, who teases Shouichi without mercy, but actually has a softer side; the competitive gamer, Tooru Miyamae, who has difficulty communicating with others; and Shouichi's childhood friend, Kyouko Touno, the sometimes immature shoujo manga enthusiast. Seiren follows Shouichi's relationships with these three girls across three separate arcs, as their feelings grow from mutual interest and blossom into something more beautiful.