Anime series which focus on puzzle solving and/or treasure hunting are usually either inherently goofy or never far from it, and this Spring 2014 noitamina offering is hardly an exception. The mechanical puzzles which compose the “ruins,” which can be deadly or just plain embarrassing if failed, are stupendously elaborate contraptions, one character goes around openly claiming to be a “master detective,” another is a scarily convincing “trap” character (one has to wonder if a pun was intended here, given how big a role actual traps play in the series), Nanae Island has such awesome futuristic aesthetics that even the denizens of Academy City would be green with envy, and the male lead is living with a sexy female NEET ghost. Put it all together and it all looks on the surface like it will be playful, simple-minded fun.

In execution, though, the series actually dramatically exceeds its potential. The first signs of that come in the first episode with Juugo's discovery that there was a method to his sexy landlady's assignment of him to the haunted room: Nanana was the landlady's friend and fellow Great 7 member in life, and she wanted her to have a companion to keep her from being lonely. (We also later learn that her previous roommate essentially abandoned her.) Though almost invariably cheery, Nanana is hardly a passive ghost, as she has a seriously aggressive streak and can say with a bright smile on her face the she does not think she can move on unless she can uncover and kill the person who killed her, whose identity was never uncovered ten years earlier despite an intensive hunt. Later on, when pressed by Juugo, she reveals that she may have other motives for wanting to stick around, too. She also feels that she must abide by her own decision never to directly tell anyone how to find any of the Nanana's Collection items or bypass the ruins where they are hidden, as she feels that promoting the spirit of treasure-hunting is what defines her and it is particularly important for her to maintain that now that she is a ghost.

But Nanana is hardly the only interesting character. Juugo seems at first like he will be just a stereotypical male lead (albeit a more physically capable one than normal), but a startling revelation about his background about a third of the way through the series heavily redefines who he actually is and where he is actually coming from. Tensai, the self-proclaimed “master detective,” proves to be clever and intuitive as well as smart (the three do not always go together in anime), and not in a way that requires everyone else to be stupid just so she can look good, either. One character who initially appears like he might be an ongoing antagonist actually ends up having motivations that are in some respects vastly more complicated and in others vastly simpler, while a side character who pops up along the way carries her own mystery, though that she has one at all is not initially apparent. Mix in a few worthy supporting characters and a nasty true antagonist who pops up late in the series and you have a lively, satisfying mix of characters who keep the series moving along quite nicely.

The overall plot progression is vaguer. Enough happens that the series avoids merely falling into a “challenge of the week” format, but the succession of shorter arcs here, which paints a deeper and more involved picture than was initially apparent, seems mostly intended to firmly establish the characters and relationships and lay the groundwork for later developments rather than actually develop what should be the main plot point – i.e., finding Nanana's killer. In fact, nearly no progress has been made on that front by the end of the final episode. The story feels more like it is at a midway point than a conclusion at the end, and a second season not eventually being animated to finish the story out would be criminal.

Nanana's Buried Treasure represents a dramatic directorial departure from Kanta Kamei's two previous lead efforts (Bunny Drop and Oreshura), but it is also a distinct visual departure, too. The character designs are mostly conventional ones by anime standards, though Juugo seems a bit more athletic than the typical male lead and Nanana is hard to resist with her charming smile. Although the CG-animation mechanical puzzles in the “ruins” can get immensely elaborate, the real star in A-1 Pictures' artistic effort is the architecture of the building and monument designs of Nanae Island, which are a marvel to behold. The animation is less impressive; while the degree of movement is fine and fluid enough, quality control in the rendering sometimes suffers. Despite playing up the curves of Nanana and landlady Shiki, fan service is actually very limited, with some focusing on the trap character and one scene in the hot springs episode even being an amusing turnabout of the norm. Less prurient fan service consists of the frequent screen shots of assorted actual game system games that Nanana plays; identifying all of them will challenge even a die-hard gamer.

Keigo Hoashi, who previously distinguished himself on the soundtrack for Dusk maiden of Amnesia, does a respectable but less stand-out job here with themes that generally hit the right tone for more comical and action-oriented moments and take a very light touch for more serious moments. Energetic opening theme “Butterfly Effect” suits the series well, while closer “A Hazy, Secret, Certain Future” is largely forgettable. Yūki Ono, who played second fiddle as Alsiel in The Devil Is a Part-Timer!, acquits himself well in the lead role as Juugo here, but otherwise the Japanese dub effort is competent but unremarkable.

Overall these 11 episodes find a good balance between humor, action, character development, and the occasional more serious overtones, all while keeping the decided silliness factor surprisingly well under control. Despite also featuring a female title character who is a ghost due to a ghastly crime, it takes a dramatically brighter and more light-hearted (and tamer!) approach than something like, say, Dusk maiden without ever entirely forgetting that a great tragedy lies at its core. That a series with such an unassuming premise wound up as good as this series does makes it a pleasant surprise.