To arm themselves for the final battle against the death god Oushuu, Akina and co. pay a visit to the Ise Grand Shrine to beseech the help of elder god Izanami-no-Mikoto, who instructs them to forge a new set of sacred treasures blessed with her own divine power. The catch is, these neo-jingi must be made by combining the powers of humans and demons. Whatever that means...
Quartet is about three girls with magical powers who are in charge of governing and protecting their town, and a human boy. There are adventures and there is action. Unfortunately, both are rather disjointed. Yasuda works hard to introduce the reader to the characters and to give her girls individual narratives that expand upon their characteristics. However, there isn't a clear theme or story line as anchor. Ultimately, it's a somber look at magical girl manga. The happiness and overzealous cuteness typical of this genre is absent. And while the school-girl skirts may fly up from time to time, there are no gratuitous panty-shots (save one at the end), replacing sexy-cute with an elegant, sophisticated sexiness. Yasuda's character designs are the most engaging. Hime, who acts as mayor, keeps a lookout on the town from telephone poles and carries a big lacrosse stick. Kotoha has the power to materialize objects that she imagines and then verbalizes. Ao has cat ears and can read people's minds. It's nothing spectacular or original, but the subtlety with which Yasuda presents them is refreshing.