Members of the Japanese girl-group AKB48 pose at an event in June

Pop goes Japan’s music scene. The top 10 singles to rule Japan’s music charts in 2010 were all claimed by two tweeny-bop groups: AKB48, the army of 48 fresh-faced mini-skirt-wearing girls, and Arashi, the quintet of lanky boys.

It shouldn’t come as a surprise; the two groups have been inescapable. Harmonization may not be either group’s forte, but the pop sensations blitzed the airwaves and advertising billboards with a cheerful zeal as the political landscape deteriorated and the economy faltered. Still, the feat is remarkable even for your typical pop act.

AKB48 clinched the top-two selling singles in Japan this year, the first time for a female group to take the back-to-back spots in 32 years, according to entertainment data tracking firm Oricon Co. on Monday. The group’s “Beginner” was the best-selling single, with over 950,000 sold since its late October release date. The girls, who seem to have a limitless wardrobe of rotating school-girl uniforms, must have been pleased: they worked hard to incorporate six new dance combinations into the beat (see video below). In the syrupy sweet “Heavy Rotation,” the second-place finisher, the lingerie-clad girls are having a blast pecking each other at a slumber party. In total, the group claimed four top-10 singles.

The all-male pop group Arashi, which means “storm” in Japanese, filled out the six remaining spots, selling over 3.7 million copies total.

Indeed, much of the two groups’ appeal draws on the careful orchestrations conceived by the Japanese pop-music marketing machine. Arashi is one of many boy bands created by the renowned Japanese entertainment company, Johnny & Associates. After a sluggish start the boys blasted onto the crowded Japanese boy-band scene in recent years with a ferocity unseen since SMAP, the boy-grown-into-man band still going strong since their pioneering debut nearly two decades ago.

Similar to their older brethren, the five Arashi members now host their own TV show and are the pitchmen for companies including Coca-Cola, mobile-phone company au by KDDI and appear in commercials for Nintendo’s Wii Party game (see video below). They were also named the “nation navigators,” a type of ambassadorial role, for the Japan Tourism Agency’s new tourism campaign “Japan Endless Discovery” in April.