Well ..our mangaka doing the best so his child can proud of his father work ...This will be a great story to tell their kids one day.
To be fair, she expected that they would either have the backup guitarist sing or else just cancel the show; she was against having the traumatized high schooler perform at all, until Oogami volunteered.Expecting the substitute with stagefright to also be the lead singer is a lot more unreasonable than her singing when she is feeling good enough to screw around.