The original sound track of Warawara Invaders.
The file format is ogg. then you can play with the ogg format compatible player.
For most musics, recommended to play with "loop playback" function.

How to access DLC contents

Steam Client > LIBRARY > GAMES > Warawara Invaders >
Click right button to Open Prorerties >
Choose "LOCAL FILES" tab >
Press "BROWSE LOCAL FILES" button >
When the Explorer opens, open the ost folder of the displayed directory >
You can see contents files.

***** track list *****
01. title.ogg
02. maintheme_01.ogg
03. shop.ogg
04. maintheme_02.ogg
05. maintheme_03.ogg
06. maintheme_04.ogg
07. boss_01.ogg
08. boss_02.ogg
09. boss_03.ogg
10. fanfare.ogg
11. resttime.ogg