What is the purpose of having this face in the subtitles/lyrics? During the first verse in the second opening to Hayate no Gotoku (Shichitenhakki Shijou Shugi! by KOTOKO), this face (O_O;) appears in each version of the subtitles;  the translated, romanised and original Japanese versions.

Additionally, the face is also included on various lyrics sites such as here and here.

Why is this? I've never seen emoticons or unicode faces in any other subtitles, and I don't see how it adds to the song at all. I know this is a series that doesn't take itself too seriously, but is there any explanation as to why this is here?
Possibly to show the reaction of the actor in the song, which seem to be surprised/heavily pressured by fact of &quot;the demon who wears goddess mask&quot;... maybe... or probably there's no purpose of the kaomoji!.. or it can be anything...
Considering that KOTOKO is a famous denpa song artist (read also What is the actual meaning of &quot;denpa&quot;?), anything goes. (Note: the Japanese title even has a star in it: 七転八起☆至上主義!)
So, what is a denpa song?

Denpa song (電波ソング) is a type of Japanese music that is intentionally strange and catchy. Common features of denpa songs include intentionally off-key vocals, nonsensical lyrics and an over-the-top tune.

Back to kaomoji...
Kaomoji is certainly rare in song lyrics, but there are some more (not necessarily denpa song). From Yahoo! Chiebukuro:


Koi no Tsubomi: (T_T), (&gt;_&lt;), (*_*), (;_;), (T^T), (T0T)/, (*_*)
Love Love Chu Chu!: (&gt;&lt;), (T_T), (#^_^#), (@_@)
Happy Succession: (^^;), (T_T)
girls: (&gt;_&lt;;), (≧O≦)
message: (-.-;)', !(&gt;&lt;)!'

(All links are link to song lyric)

Last but not least, Ryuichi Kawamura has a song titled 〔&gt;_&lt;〕.

Personally, I don't consider Shichitenhakki Shijou Shugi! as denpa song, but perhaps it's because I'm already used to IOSYS.