I am a layperson so take that into account, but I find several characters in anime and manga who resonate with my experiences living with ADHD, and what I've researched about it.
One character especially is Katarina/Catarina Claes from the novels and anime "My Next Life as a Villaines: All Route Lead to Doom."
She zones out, she dives head first into things she finds interesting, she's often hyper and literally climbs trees. She hates things that bore, and she certainly is impulsive.
It was this quote in particular (in her past life) that really spoke to me:
Acchan... I can't... can't go on. I leave the rest... to you..." With that, my best friend slammed her textbook shut, before dramatically planting her forehead down onto the stack of notes I had printed.
"Wh-what are you even saying...? It hasn't even been ten minutes since we started! If you keep this up, you'll drop out of the school system for an entire year!"
"..Nghh... b-but... reading these endless lines in this thick reference book only makes me sleepy... there's no avoiding it. There has to be some sort of curse in this terrible reference book..."
Saying so, my friend sighed deeply. And with that, the High School entrance exam study session ended, in all of ten minutes. Although she was physically capable and did well in sports, she was apparently hopeless in her studies. It wasn't like she was bad at studying - she simply had no interest in it, and was the sort of person who didn't care about matters that bored her.
--My Next Life as a Villainess Vol 2 by Satoru Yamaguchi
I would love to see an except'sexpert's opinion. But the fandom is pretty much Unitedunited.