Shame / Embarassing, most likely.
Teru has always seen herself as a failure and can't live up to a Hero title, always compare herself to other heroes, and keep chasing, trying to be like her Sister. In the proccess, she left her real self behind (the little Teru), and with every Henshin, she's killing her real self to chase the ideal that's her sister (the Many Shy).
In the end, she accept herself for who she is, she's not as grand as hero like Stardust, Century, or Lady Black, and not as skilled as Spirit or Mian Long. But that's fine, because she chose to be close to you, the little candle you light on when you're having a lights out.