If you're looking for manga similar to I Became Friends with a Delinquent Girl, you might like these titles.
A "delinquent" who freezes up and says violent things when around women meets a small girl in the library when he's out studying. To his surprise, she tutors him, even though an elementary student shouldn't be able to. As it turns out, she's a high school student and his classmate; she's eager to befriend him. Also surprising to him is the fact that he isn't afraid of her. Could it be because he sees her as a kid? Or does he?
After a misplaced confession lands the letter of Touno Hitomi in the locker of Saijou Nagisa, both of them experience feelings of attraction towards each other.
The somewhat foul-mouthed high school girl, Kobushi Jun, reunites with Tanba Terumi, who she crashed into during a basketball match back in middle school, on the train while commuting to school. Jun is drawn to Terumi, even as Terumi manipulates Jun. As these two worry about and misunderstand each other, how will their romance unfold?!
Everyone in class fears Ai. She’s always covering her face with a mask, wears a Hannya jacket, and hardly speaks a word to anyone. She must be a delinquent! Two of her classmates are told to give Ai her homework handout but are too scared to approach her. Luckily for them, the class representative - Watanabe - offers to do it in their stead. Little do they know that Ai is a gentle soul, and that their class rep is the actual delinquent!
"Hino-chan, you're cute today too." Harukaze Hino is a high school girl who's not confident about her appearance. She's made fun of in class and many of her classmates even call her ugly. Despite all of that, her yankee classmate, Kurobane Raou still tells her she's cute!?
Seemingly delinquent high schooler Nakamura-kun is actually shy at heart with dexterous hands and as skilled as any domestic goddess. He falls for fellow student Hayashi-san, a beautiful ojousan and honours student at their school but...
In order to get the attention of a boy who really likes robots, a girl lies about being an "android"...?!
Tadashi is in his second year of junior high school and is a member of the handicraft club and loves nothing more than knitting. Unfortunately he's in a secret relationship with Saya, the member of a notorious all-girl gang, who says she will kill him and herself if anyone ever finds out about it.