When I recommended Chi no Wadachi earlier in this thread, it was for similar reasons. It's interesting that people are recommending stories about characters that don't quite fall under the definition of full NEET here.
Seichii Osabe, the protagonist, ends up living as a recluse when he reaches adulthood, working a deadend job, with no close relationships or people to rely on but himself. This is in part due to his mother, Seiko, who abused Seiichi as a child and ruined his life, to the point where he hallucinates about her nearly twenty years later. The manga has heavy subject material, but worth checking out if you read Aku no Hana/The Flowers of Evil. It's still ongoing, to my knowledge.