An extension of the summer-arc in the Air TV-series, showing more of what happened during Kanna's, Ryuya's and Uraha's journey to find Kanna's mother.

The world of Yozakura Quartet is actually not one, but two worlds: one of humans, and one of youkai. Despite appearing mostly human, youkai may have animal like physical traits, along with a number of special abilities. Normally youkai are confined to their world, but some have found their way into the realm of humanity. As a symbol of peace, and a bridge between the two realms, a city was constructed within the protective barrier of seven magical trees, otherwise known as the Seven Pillars. This city of Sakurashin is home to both humans and youkai, with the peace between them maintained by the Hizumi Life Counseling Office. The director of this office is Akina Hiizumi, a teenager with the inherited family ability to perform “tuning,” which can send harmful youkai back to their world permanently. He is aided by a group of girls, including the town’s 16 year old youkai mayor, Hime Yarizakura, their town’s announcer and resident telepath, Ao Nanami, and Kotoha Isone, a half-youkai who can summon objects just by stating the object’s name. As new residents enter and mysterious events begin to take place, this quartet of protectors and their closest friends must continue to guard the city of Sakurashin, and maintain the fragile balance of peace between humans and youkai.

An OVA based on the Hoshi no Umi arc of the manga spanning chapters 26-34. This arc focuses on Rin Azuma, a Jiang-Shi yokai resident of Sakurashin adjusting to her new life in the city and working for a ramen shop. One day her former friend Zakuro Kurumaki invades Sakurashin to capture Rin and convince her to join her in destroying the city with the other yokai hunters as well as Enjin Hiizumi, the main antagonist of the series. Akina Hiizumi and the other members of the Hiizumi Life Counseling Office take action to save Rin, 'tune' the yokai controlling Zakuro and protect the city. (Source: ANN)

In the anime series, the members of Six Gravity and Procellarum are all living in the same dorm building. Hajime Mutsuki and Haru Yayoi, the oldest members of Six Gravity, are first year university students. Each episode of the series will feature a different main character. (Source: MAL News)