You get this once you arrive back at Francis' home in the opening stages of the game. After the intro section where you first strum on stage, Francis takes the cable car into town. In town you'll encounter a funicular railway (a lift / elevator) that goes up. You need to head up, go left, up the next one and go right to the end. Looks for the "door" icon that's activated with "Y".
The achievement will pop once you enter the second room and talk to Francis' mother.