The pack contains four tracks:
Hyadain - Hyadain no Kakakata Kataomoi-C: https://www.youtube.com/watch?v=pzpqMSaf13k
Hyadain - Hyadain no Kakakata Kataomoi-C (off vocal): https://www.youtube.com/watch?v=tA-frKY2zJA
Hyadain - Hyadain no Joujou Yuujou: https://www.youtube.com/watch?v=1ESF1tw6T3k
Hyadain - Hyadain no Joujou Yuujou (off vocal): https://www.youtube.com/watch?v=PNipDigsEvE

To use this you need both beardlib and superblt

extract the songs you want to use, drag them into the mod_overrides folder and you should be good to go