Lacunosa Town – Pokémon Black/White

This is Lacunosa Town” from the Nintendo game “Pokémon Black and White”.
It was composed by Hitomi Sato.
The movement of the melody is impressive.
The first half is in Bb minor, and the second half (from bar 25th) modulates to Db major, a relative key.
In the first half, bVI-v-v/i is repeated, giving it a swaying feel.
In the second half of the piece, when it modulates to Db major, the ii-V of the destination key is used in bars 23-24 to make the modulation smooth.
When it modulates, there is a cheerfulness as if a fog has lifted.
At the end of the song, in bars 29-30, use the “Ohdo progression(王道進行)” IV-V-iii-vi, which moves quickly toward the end of the song.(The melody here is the same as in the first 9-10 bars.)

I think it’s rather easy to play because there are many open strings.