He's the doll in the suitcase given to Masaru by his granfather in case something bad happens. He was instructed to find Shirogane, the current wielder of harlequin.
Harlequin is a relatively old doll, his exact age is unknown and never specified. He is dressed like a pierrot and has long white cloths coming from his head. His face is that of a white mask, missing its left eye. His left arm is broken, and with the broken left arm tied to the right arm, he wields Olympia's left broken arm in his right one to use as a weapon.
Abilities and PowersEdit
Swirling Tiger: 
Harlequin rotates the top of his body destroying everything on the way with his spin. This attack is strong enough to destroy an entire puppet.
St George's Blade: 
A blade comes out of his right forearm and he uses it to attack.
He was created by Shoji Saiga for Shirogane to use him to protect his grandson.