pencil and story: Haruki

The volume is in Japanese, so I can only guess the story.
Fantasy tale featuring an elf girl who seduces a human blonde of the same age.
The blonde in turn seduces a friend with brown hair.
The leitmotif of the relationship are "penises" that magically appear and disappear, passing from one girl to another.
Eventually the girls end up living together, of course.
The era of the setting is not clear, since at times it seems to be Medieval Japan, while at others it is clearly in the present day.
A somewhat stylized drawing and the inevitable censorship of the private parts does not help, but you can guess the plot.