HY were the most successful Japanese indie rock band of the 2000s, although it must be noted that the term "indie" in their country applies solely to label status, without any musical connotations. HY's fifth album, Hearty, has been characterized as "genre-less," and that's a fitting description, seeing as the band specializes in sweet, accessible pop/rock with both hip-hop and hard rock influences found in the mix. Their pop prowess accounts for the fact that within a few years of their career they broke several commercial records, despite being the rarest of Japanese bands — the one that never released a single.
HY were founded in Okinawa by five high schoolers: Hideyuki Shinzato, Shun Naka, Shinsuke Kyoda, Izumi Nakasone, and Yuhei Miyazato. They took their name from their hometown Higashi Yakena and built their popularity on street performances, soon achieving enough recognition for the limited release of their first album Departure (2001) to get sold out, prompting its nationwide release the next year (2002) through Climax Entertainment, a small label with which they stuck with regardless of the juicy offers from majors. Active touring further improved HY's status: in 2002, they appeared at a musical festival in Paris, played their first set of shows throughout Japan, and shared the Budokan scene with Linkin Park. Consequently, their second studio album, Street Story (2003), became the second indie million seller in Japan and shot to number one of the general album charts — a feat never before pulled off by an indie band, but repeated by HY's next two discs, Trunk (2004) and Confidence (2005). After that, HY easily sold out all 47 gigs of their Japanese tour, which was followed by concerts at the Budokan and Osaka-Jo Hall; the former being broadcast live on the national TV. HY concluded their touring with seven dates in the U.S. and Canada and a series of club shows in Japan in 2007, before taking a break until 2008, when they returned with Hearty (number two on the charts) and another nationwide tour in 2008.