Very interesting! Its a Woodblock.

Here is what woodblocks sound like.

Luckily for us, the song’s wiki page covers this.

I just listened to that song, and I didn’t hear any drums in it. There’s what sounds like midi-harpsichord doing a precussive run throughout though.

Is this the song? https://www.youtube.com/watch?v=uVCAnYTkyIo

What drums of any kind in the Delfino Plaza theme are you hearing? 🤨 There are no drums in the official version in the game. Are you listening to a cover of it, perhaps?