Homunculus is a Japanese manga series written and illustrated by Hideo Yamamoto. It was serialized in Shogakukan's seinen manga magazine Weekly Big Comic Spirits from March 2003 to February 2011, with its chapters collected in 15 tankōbon volumes. Susumu Nakoshi is a 34-year-old homeless man living out of his car. For two weeks, he has declined his fellow homeless men's invitations to set up a tent with them, preferring to sleep in his car. However, one day, he is accosted by a strange-looking man searching for participants to subject themselves to trepanation.