The mischievous Hatsune Yaku. For the record, Yaco is a boy. He is cosplaying as Miku. He has a playful but bright and cheerful personality. He is active and innocent. Because of this personality, he causes a lot of trouble, but he always gets away with it thanks to protagonist luck(?). (His personality is indeed based on Miku.) He is always imitating Miku. (Yaku Beam, hearts, poses, etc....)