With the best Japanese pop bands it's always hard to tell whether they are serious or not, and this goes in full for Sotaisei Riron, who outdo most of the country's sugary popsters, but seem to have a tongue firmly planted in cheek at all times.

But then, with the band's name translated as "Theory of Relativity," how can you not expect quirkiness? The most immediate feature of Sotaisei Riron is the vocalist, who sounds like a nine-year-old girl from anime -- child-like even by J-pop standards -- but her exaggerated innocence is actually a counterpart to music, which has none of the bland, string-backed harmonies favored by regular Oricon inhabitants.

Instead, the band utilizes a whole lot of jangly guitar textures usually associated with alternative rock -- you can trace them all the way back to the Pixies or even Number Girl -- but these makes them sound so airy and melodic they become the aural equivalent of a bunch of adorable kittens playing in the garden on a warm summer day.

The obvious irony already scores a point for the band, but the best thing about Sotaisei Riron is that their songwriting approach is no quick gimmick; they enable them to crank out some memorable and well-developed tunes with good hooks and plenty of depth beneath the cute facade.

The sound is not entirely unique -- the band has similarities to Stereolab, old '70s feel-good movie soundtracks and even compatriots Spangle Call Lilli Line -- but the truth is, no one this side of Isan is so good at writing songs that give off such a warm fuzzy vibe as Sotaisei Riron do on Synchroniciteen.