Yamaha's site for the Ukulele book weirdly doesn't include credits for the last six songs, but
I found them at Tsutaya and yup, Shiho Fujii for the NSMBU aboveground BGM. Neat. Also gives Kenta Nagata for the NSMB2 aboveground BGM.
Have you listened to the album and checked that the SM3DL aboveground theme here is Hama's main theme? I'm sure it is, but the reason I didn't put it in the notes before is because it's called "Super Mario 3D Land Theme" elsewhere and the name would be different here.