I found this manga some time ago, it's full name Boku no Kokoro no Yabai yatsu, or the Dangers in of my Heart, by Norio Sakurai. It's description sounded super intimidating, saying how the MC was a sociopath killer or some weird stuff like that... And it was a total lie.
The manga deals with Ichikawa, our protagonist, an introverted 14 years old teenager really deep in his edgy -and very cringey- phase who founds himself slowly falling in love for this extroverted and beautiful girl called Yamada, whom he initially believed he hated.
But as he gets to know her better, they become friends and slowly something more. That way, we go along him in this awesome journey seeing how he grows up and works harder to become a better person, resulting in very funny romance and with a great development.
To see if you like it, take a look at this fans-translation of an extra the author posted in his twitter: