What is the name of this anime with this ending song?

Please help I cant remember the name of the anime and i have been searching through my history with no luck.

I think there was light colors and the ending song was centered on a girl that wakes up and drags herself to school and is boredly going through the school day. Near the end of the song a huge tree sprouts and grows around her (i think in the classroom) and the singer sings really fast i think the last lyric was "hundee" the singer was singing in Japanese and that's not even a Japanese word i watched it subbed i think the song was about her saying she doesn't want to go to school or she doesn't want to wake up or something. The art for the ending song i think didn't have a recognizable character in it and the art i don't think wasn't matching the same drawings of the show.