Aiko is one of my favourite female singers. She has got a sunshine personality to match her cuteness! Love her voice and she's got a pretty unique style of composing songs.
This is my fave song of hers called 'Ama no Gawa' / '天の川' meaning Milky Way (Celestial River):
'Eriashi' / 'えりあ し' :
Aiko being her exuberant self tossing plushies to her fans: