I generally don't like songs where people are screaming everything, but this is one of the few exceptions to that (for me, at least). The song is a remix of the third Bleach opening.

Lyrics (Japanese):
Kimi wa kimi dake shika inai yo
Kawari nante hoka ni inainda
Karenai de ichirin no hana

(screaming, not sure what they're saying lol)

Kimi wa kimi dake shika inai yo
Ima made mo kore kara saki ni mo
Tatoe kimi igai no subete no hito wo
Teki ni mawasu toki ga kite mo
Kimi no koto mamori nuku kara
Makenai de ichirin no hana

Lyrics (English):
You are the only "you"
There is no such thing as your replacement
Don't wilt away, single flower

(screaming)

You are the only "you"
Till now and from now on
Even if there comes a time
When the whole world becomes our enemy
I'll protect you
So don't give up, single flower