Atomic Heart is the sound of a band fully defining its identity and taking its rightful place in the pantheon of Japanese pop-rock. Released in 1994, Mr.Children’s fourth album is the one that blew the group up into a full-fledged phenomenon. Its earlier records had been big, especially 1993’s Versus, but nothing like this. Atomic Heart hit the top of the Japanese charts straight out of the gate and became a multi-Platinum album, generating two enormous hits with the much-covered “Cross Road” and the award-winning “Innocent World.” On its first three albums, Mr.Children had touched on power pop, alt-rock, danceable grooves, and more, but on Atomic Heart it seized on the sounds that were most firmly in its strike zone so that a signature sound came completely into focus. The results not only cemented the band’s superstar status but also pretty much set the template that it would use as a stylistic springboard for decades. “Dance Dance Dance” and “Jealousy” reboot ’80s dance rock à la Duran Duran and INXS for the ’90s alt-rock generation, the latter taking a slinkier route and the former being a more in-your-face proposition. “Love Connection” brings another brand of locomotion to the table with its rocked-up Motown-style soul grooves, complete with punchy horn punctuation and a slamming beat. “Classmate” leans into a slightly later period of American R&B for inspiration, sporting a lush, ’70s Philly-soul feel, with electric sitar and a horn section sweetening the setting. The poppier side of Mr.Children’s sound is in full flower on Atomic Heart as well. The hit “Innocent World” is the kind of cinematic pop rocker the band had been busily perfecting for years. “Amenochihare” is such an easy-rolling slice of pop-funk confection that it’s hard to believe it wasn’t released as a single too. And the dramatically unfolding “Over” closes things out with the elegant, Beatles-tinged pop vibe that would remain in the Mr.Children wheelhouse for a very long time to come.