Yochu

(from ebookjapan):
Hideo is an eccentric young man who loves insects. He has been affected by a strange disease that causes cotton to pop out of his wounds, transforming him into a monster, just like an insect that metamorphoses completely from chrysalis to butterfly.... He swallows people without their awareness and slaughters them, but what is his end result?　And then there are others who have been affected by a mysterious disease that causes an ugly transformation.... What in the world is going on on this planet right now? Here comes the most traumatic work of Koga's manga!

While the content of the stories differ, the title is likely a reference to Ranpo Edogawa's short story of the same name.