God Only Knows
Series: 神のみぞ知るセカイ
Series (Romanized): Kami nomi zo Shiru Sekai
Series (English): The World God Only Knows
Artist: Oratorio The World God Only Knows

Difficulties and Style:
God Of Conquest - 10 - Mixed
Extreme - 9 - Mixed
Hard - 6 - Arcade
Normal - 4 - Arcade

Charter:
JoldNoteC

Sources:
Video:
https://www.youtube.com/watch?v=KZBgRDMyXzw
Oratorio The World God Only Knows - God only knows (Full Version)
Triplicat
Preview: obtained from an AminoApps blog reviewing the anime (link deleted to pass auto checks)
Background: made by ASMURAEFFECT (guessing from watermark), obtained at ZeroChan (link deleted to pass auto checks)
Lyrics: Kami Nomi Wikia (link deleted to pass auto checks)

Alternate Videos:
AMV by Gadet_99 (eng+spa subs)
https://www.youtube.com/watch?v=B30fm_n9RB0
God Only Knows AMV (Kami Nomi zo Shiru Sekai Opening) || sub español HD
Gadet_99