This isn't a straight series where each episode connects to the next. It’s divided into 3 arcs. First we meet Saya Tokido. A girl who fights mysterious shadow people trying to find a mysterious treasure. This story takes place before the events of Refrain. Next we have Sasami Sasasegawa who for some reason changes into a cat that only Rikki can understand. These events occur after Refrain. Finally we meet Kanata Futaki, Haruka Saigusa's sister it takes place after Refrain. However the first half of her story does not start here it takes place before the events in Refrain. It ends here and takes place after the events in Refrain.
(Summary Courtesy of Anime News Network)
8-episode OVA series that premiered on January 29, 2014.
Animated by JC Staff.
Animated by Sentai Filmworks.
See related series,
Little Busters! and
Little Busters! Refrain.