This song has a simple but effective instrumentation; piano, drums and bass for the most part, and brass here and there. It manages to be catchy and interesting because of the melody and chords in my opinion. It's hard to point at something specific, yet the song in its entirety just has a certain, very definitive appeal, especially the ending where it almost has an improvised feel.
This song is from what one could think of as the 'middle period' of Pizzicato Five; they had acquired Maki Nomiya as a singer, and not yet ventured into the experimental things they did in the late 90's. Another, shorter version of it is on "Big Hits & Jet Lags '94-'97'", and that's about the only difference between the two.