Gerekushisu

Tatsumi Onishi, a baumkuchen maker, falls in love for the first time at the age of forty. However, he is literally a lost cause. One after another, unexplainable and unnatural phenomena befall Onishi: one after another, he becomes something that can no longer be called a person. Will he be able to bake baum again? (Source: Kodansha, translated)