noun
collecting maniac; obsessive collector
A person who is fanatical about collecting things; often used in a slightly humorous or self-deprecating way.
彼は切手の収集魔で、部屋中が切手だらけだ。
He's a stamp-collecting maniac; his room is full of stamps.
私は本の収集魔だから、本棚がすぐいっぱいになる。
I'm an obsessive book collector, so my bookshelves fill up quickly.