More popularly known as "Nujabes", Jun Seba passed away in late February in a car accident. He gained popularity when he produced a nice chunk of the music for Samurai Champloo, using a jazzy, melodic production style. I'd even go as far as saying he's like a Japanese J Dilla, and unfortunately they share another similarity.
I find it kind of fucked up that his label kept this secret for, like, 3 weeks, but it makes sense. The fact that no one found out before today shows how mysterious he really was. You rarely see interviews or pictures of him partying besides DJing, but with music like his, you don't need a public persona.
Much like Dilla. See?
I'd put this beat in my top 20 favorite beats ever.