Ocarina

Daughter of the former Hawk King, Ocarina stayed behind with the mazoku when her father left. She is a mazoku herself, and has the ability to change between her birdy form (which we see her in at the beginning of the manga) and her human form, though she still retains wings. After Ocarina goes into her human form for the first time in v10 she decides to stay like that for the rest of the story.

Nothing is known about Ocarina's past prior to Bass handing her the baby Sizer, but from then on she raised Sizer and was her only friend as she grew up. Ocarina knew the truth about Sizer's 'abandonment', but Bass threated to kill the both of them if Ocarina let slip, and so Ocarina was forced to be silently supportive as Sizer grew up, hating Pandora and the humans for rejecting her.
Although Ocarina is far older than her young charge (she's over 500 years old, since she admits to fighting against Vocal when he tried to overthrow Chestra) and raised her from an infant, she sees Sizer as above herself and the word 'Sizer' never leaves Ocarina's lips without a 'sama' being attached to the end. She is fiercely loyal to Sizer, and her primary concern in life is the wellbeing of Sizer, physically, and emotionally. Essentially, Sizer is Ocarina's life.
Of course, Ocarina is far from just a subservient mazoku who follows orders without question or thought. She's probably the most cheerful and optimistic member of the group, and is a fierce fighter in battle. She doesn't interact much with the other characters since she's always by Sizer's side, but she grows fond of anyone who helps her mistress recover from her past. She also enjoys teasing her father. ^.^
And seriously, I could try for a thousand years to explain just how devoted to Sizer Ocarina is and the depth of that devotion, but I'd never come close.

Ocarina doesn't use any physical weapons during battle, but favours the "Hou Ou Sen Pa", a type of whirlwind exploding magic, or something. ^_^; As far as I know it means "Thousand blows of the Phoenix". It's powerful, and only Vocal has worked out a way to stop it (*shakes finger at Vocal* Perv!)
Her special talent is gathering information, and unfortunately this means that she doesn't appear in the story very much. =(
Of course, sometimes the information is a little outdated by the time she returns with it, and sometimes it might even be completely irrelevant. (Did you know that Orgel like penguins and bananas? ^.^)

This site is owned by Wyrren Sarrasri, and the Violinist of Hameln manga is (c) Watanabe Michiaki. If he turns his head for a second though, Wyrren might run off with Clari. ;D