Becoming uninhibited with 気が大きくなる


Grammar Explanation

ひとりぼっちの○○生活 » Volume 1 » Page 22

Bocchi was up late reading a book on how to make friends. At the time, she was overly enthusiastic, but at school the next morning she finds her social anxiety has returned.

ぼっち:
(よる)()(おお)きくなる
“Last night I became uninhibited.”