As previously mentioned, KuKuDoDo's music is unequivocally denpa at its barest denominator, a fact that the duo is proud to endorse. Of course, the genre is merely a loose descriptor for a mish-mash of cute/moe JPop, chiptune, high-energy dance tunes and whacked-out compositions, but so far they fit under the umbrella just fine. Furthermore, some of their songs are a bit more "normal", sounding more like I've Sound's earlier gritty trance than cartoony. So it's fair to say that while denpa is at the core of their creativity, they're willing to explore connected avenues. Although they haven't composed any proper eroge or anime theme songs yet, they are offering their services and are looking for staff as we speak.
Not unlike their peers in IOSYS (with whom KuKuDoDo collaborated by way of Birdtune), Shanghai Alice's popular Touhou STG series plays a huge part in their musical inspiration and by proxy, their marketing ability. But you shouldn't let that stop you from giving them a chance if you've gotten sick of constant Touhou rehashes, as the influence here is certainly palpable but not overwhelming by any means. The fact remains that ZUN provides amazing blueprints for budding artists to build off from and propel themselves into a solo career, which is the step where KuKuDoDo feat. Gumi are at right now. Additionally, some of their earlier songs also made use of Hatsune Miku's charming voice, but the original musical arrangements far outshined the virtual diva's waning appeal.
But KuKuDoDo's influences extend far from the insular confines of Japan. In fact, this guy is a full-blown fan of England's legendary synthpop years, citing bands such as Depeche Mode, Yazoo, Erasure and KajaGooGoo as primary sources of inspiration. Who knows, maybe his artist name is a direct reference to KajaGooGoo? At any rate, KuKuDoDo wanted music to play a big part in his life a number of years ago, citing that as a child, he wrote "I want to be a roller disco DJ" on a 短冊 (Tanzaku), those long pieces of paper that people use to write down their wishes at a 七夕 (Tanabata) festival. He was "dormant" for a number of years, but took it upon himself to realize his wish from 2000 on, when he began experimenting with Cubase and other DAW tools. Very little is known about Gumi herself, unfortunately. Holic Service also have a PR lady, Ponza, who's in charge of events, marketing and so on.
Let's move into discography territory. So far, KuKuDoDo feat. Gumi have released exactly 22 songs spread across 9 CD releases, including 2 singles and 2 mini-albums. They first made a name for themselves by releasing some online videos of anime theme song remixes, but their first original song didn't even feature Gumi on vocals but rather Hatsune Miku. This was on the 「れいんep.」, their first single which came out in April 2008 and also featured three other original tracks, including the unique 「コイノカイロ」, which was renamed 「恋の回路」 later on. Holic Service wasn't even formed then, so Birdtune handled the distribution of this first single.