Hell Teacher Nube (Werewolf Transformation)

This horror-comedy manga dates from the mid-90s. The second chapter of Vol. 14 is titled "The Proud Werewolf" and tells the story of a wild boy (raised by wolves?) who learns to accept his inner lycanthrope. The scans are in the original Japanese.

We start out with the boy being visited by Nube and a friend, who reveals the full moon, cuing a quick transformation and reversion:

Later on, they visit the boy during another full moon. This time some sort of wolf spirit appears to the boy and initiates his transformation.

Here's a shot of him running off in wolf form. He looks a bit like Lycanthrope Leo...