"Prolific" doesn't even come close to describing Hideki Kaji's career. Since the mid-90s, the Tokyo artist has been putting out albums and singles of upbeat indie-pop music at a constant clip. None of his releases are amazing, but his entire discography is still consistent. He also hasn't achieved widespread popularity — the closest Hideki came to fame was in 2009, when he was mugged in Sweden while dressed as a pineapple (he was filming a music video). His latest, "Blue Heart," won't fix that popularity problem, as it's another collection of wide-eyed pop that finds him in the same element he's been occupying for the last 15 years. It's another solid release from an artist who, while never spectacular, is consistent.

Kaji's overall sound never changes — guitar-centric pop anchored by his cheery singing — yet he does this style so well it's hard to criticize him for not mixing it up much over his career. The best songs on "Blue Heart" barrel ahead gleefully unaware of anything else, like the tropical flavor of the title track and lead single "B&W Marble Chocolate," which uses horns and female vocals to peppy effect. On the back half of "Blue Heart," Kaji brings in more keyboards, giving tracks like "Blue Jeans" and "Boring Saturday" an electronic spark. His lyrics, meanwhile, are fluff; Kaji singing about ginger ale and director Jim Jarmusch on "B&W Marble Chocolate" or playing soccer on "Boring Saturday," which also documents all sorts of other bland activities Kaji might do on the weekend.

The biggest argument encouraging Kaji to not tool around with his sound too much are the songs on "Blue Heart" that do sound different, all of them incredibly weak. Ballad "I'm Like A Mirror" doesn't even try to build up to something exciting in its three-minute duration, making it the biggest waste of track time here. Similarly, grinding "Mellow Yellow Spring" isn't much better, while "Tu-Tu Boom Boom" attempts a drive-in-movie-theater swing that ends up sounding tacky — forced nostalgia over a style nobody is clamoring to hear. "Blue Heart" is proof that Kaji doesn't need to experiment, because he's so good at one sound, there isn't a point to hearing him do something else.