Wikipedia
Jubokko
is a yōkai tree that appears in many books related to Japanese yōkai, including Shigeru Mizuki's works.
It appears in former battlefields where many people have died, and its appearance does not differ that much from ordinary trees. Since it becomes a youkai tree by sucking up large quantities of blood of the dead, it lives on human blood. When a human being happens to be passing by, it captures the victim and, changing its branches into the shape of a tube, sucks the blood out of the victim. The Jubokko that sucks life out of human beings in such way always maintains a fresh appearance. When a Jubokko is cut, blood trickles out. It is said that a Jubokko branch could heal and decontaminate an injured person.