This was bought from a street trader in Japan. We have never seen it in any shop.
It starts as a plastic object that does not give away it's secrets! But it articulates in an ingenious way, to reveal a blue biro at one end and a red one at the other end. Also the pattern of lozenges along its length changes to hearts when you move it to the pen position.
Maybe not the easiest pen to write with, given that it does not have a round cross section. But a very clever mechanism!