Hatsune keeps her backstory and real identity a secret. Her public persona is a flawless idol and musician, kind, gentle, polite and always smiling. Hatsune accidentally bump into a her-half sister Uika. 
While walking through Tokyo disguised under her usual cap and sunglasses, Hatsune, living under her sister’s name, Uika Misumi, accidentally bumps into the real Uika, the half-sister whose dream and identity she stole years ago.