Outside of SEGA he also remixed Captain Straydum's "Fuusen Gum" for the 1st ending theme of the 2006 anime Gintama, though he went uncredited. His music is broadly defined as J-Pop, but can be quite hard to categorize. He's skilled at mixing Japanese techno, funk, soul and hip-hop elements to create a unique and vivid sound.
Additional work was created under the name skankfunk, including a few tracks of the soundtrack for the anime Air Gear (a series akin to Jet Set Radio in premise as well as musical style) and a remix of "Under the Spreading Chestnut Tree" for the DVD Dance no Chikara. He used this name due to being part of SEGA at the time. This name has been used again for Naganuma's ongoing contributions post-SEGA employment to the Yakuza and Super Monkey Ball series.
In 2012, he contributed the track "LUV CAN SAVE U" for the 20th installment of the arcade rhythm game Beatmania IIDX, produced by KONAMI.