The scene context is… greeting a high school class.
Midnight is not amused at Mt.Lady's choice of pose.

More detailed explanation: They're in a school learning to be heroes and invited Mt. Lady (the one in the foreground, has the power to grow really big) to give a talk on interacting with the press since she's good at it (she's a newbie but has a lot of good press despite collateral damage (what with being a giant in a urban area)). She has a tendency to… uhh… emphasise certain assets (can you guess why she's popular?). That said, she is good at handling the press and will show later on there is more to her than being a glory seeking blowhard.

The person in the background is Midnight (power is that her exposed skin releases a gas that puts people to sleep) who is a teacher at the school. She has a bit of a rivalry with Mt. Lady who called her old on tv.