Hideki Naganuma is most well known for his work on Jet Set Radio, but he supplied music to countless other SEGA games over th years. Naganuma left SEGA awhile back, and many were hoping to see him work for Nintendo. Naganuma was hoping for the same, but apparently Nintendo didn't have anything for him.
"To tell the truth, I tried to be an employee of Nintendo twice in the past, after I left Sega. But I didn't pass. They said that there's no position that I can display my ability to the fullest. That’s the reason why Splatoon didn't need my music."
Many people think that Splatoon could have been well served by Naganuma, but it just wasn't meant to be. Who knows, maybe Nintendo will scoop him up sometime down the road when the right project comes along.