compulsive note-taker; note-taking addict
Colloquial term for someone who obsessively takes notes on everything, often to an excessive degree. The 魔 suffix adds a playful 'demon' or 'addict' nuance.
彼はメモ魔で、会議中ずっとノートに書き込んでいる。
He's a compulsive note-taker, scribbling in his notebook throughout the meeting.
私もメモ魔だから、スマホのメモアプリが手放せない。
I'm a note-taking addict too, so I can't live without my phone's memo app.
Compound of メモ (memo, note) and 魔 (demon, addict). The 魔 suffix is a common colloquial pattern for describing obsessive behavior.