Sonic X had a special one time charecter named cosmo she became a fan favorite then they ruined them selves and killed her there any way base story line is her species was killed by the Meterex so she left to find sonic she found him and his freinds but tails fell in love with her he admited it himself so it was adorable.

Yes I know the video is in japanese but they said its sadder tell me if you think her death was cruel to tails or not.