Happiness OST Part.1 - Joe Layne

01. What Lies Ahead

Happiness OST Part.2 - Isaac Hong

01. Pain
02. Pain (Inst.)

Happiness OST Part.3 - JEMMA

01. ENIGMA
02. ENIGMA (Inst.)

Happiness OST - Various Artists

01. What Lies Ahead - Joe Layne
02. Pain - Isaac Hong
03. ENIGMA - JEMMA
04. EUREKA!!! (Drama Edit) - Joe Layne
05. Portrait - Joe Layne
06. REALISE (Drama Edit) - Joe Layne
07. Chaos - Joe Layne
08. Eruption - Joe Layne
09. Outbreak - Joe Layne
10. MAGIC (Drama Edit) - Joe Layne
11. Some Day - Joe Layne
12. HIGHER (Inst.) - Joe Layne
13. The End (Drama Edit) - Joe Layne
14. Boundary - ONG SUNG EUN
15. NEXT - Yoon Chae Young
16. Resist - LIM MI HYUN
17. The Cage - Hyunpill Shin
18. Unhappiness - LIM MI HYUN
19. Who - Park Jung Eun
20. Unknown - LIM MI HYUN
21. The Apartment - Yoon Chae Young
22. Humanism - ONG SUNG EUN