When I Repaired a Gal's Bicycle, She Became Attached to Me.

Kousei Kutsuzawa is an introverted boy with zero friends. One day, as he was walking home alone as always, he bumps into the class's most popular girl, a beautiful gal sought after by every boy. After saving her from falling and repairing her bicycle, he plans to leave right away... but she looks at him with admiring eyes. An introvert and a social butterfly, two people who were never supposed to cross paths. Awkward yet irresistibly drawn to each other, their youthful rom-com story begins. (Source: Overlap, translated)