Negative Happy Chainsaw Edge (2007)

Yosuke, a typical slacker kid dozing his way through school, showing nothing in the way of ambition as he quietly mulls over the death of a close friend the year before. He is clever enough and full of smart comments but just doesn't seem to see the point of much in life. That changes when he meets Eri by chance, late one night. She is a beautiful young girl, herself nursing a tragic loss, and for Yosuke it is love at first sight. So what to do when a giant falls from the sky, determined to do battle with Eri (the young girl armed with a brace of hidden knives, as this is obviously a regular occurrence)? Yosuke finds his purpose-he must help the girl he loves, never mind the fact that she is far stronger and better equipped for this battle than he.