Introvert Tsubame is a lonely High School GirlIn-kya na Tsubame wa Bocchi JK; 陰キャなつばめはぼっちJK; Introvert Tsubame is a lonely High School Girl

A short prequel to [Introvert Tsubame wants to change](https://mangadex.org/title/1007ec9d-af06-4f22-80a7-3934f02d30b7/introvert-tsubame-wants-to-change), depicting her gloomy High School days. Originally released as a 20-days extra contents for the original series, Grande later published this manga as an independent book.