Shimotsuki-san Likes the Mob (WN)

When I met him, I realized that I was a ‘mob character’. My childhood friend, my best friend, my stepsister, and everyone else fell in love with him. But there was one girl who showed a completely separate face only in front of me. I’m not sure what to make of it. Normally she doesn’t talk much, but she’s all talk when she’s in front of me. She smiles only at me. Even though she was the main heroine, she fell in love with me, a mob character–this is my story. This is a romantic comedy about a dull mob character.