That's a very cool item! I collect Tezuka's volumes now, but don't have any retro-Japanese stuff. Is this a wraparound cover? Almost looks like it could be....
No, just a regular digest sized book. Most of the Astro Boy stories were originally serialized in the antologic publication Shonen (weekly I believe), but in some cases a story was featured in a supplement: the first episode of this story "Yellow Horse" was serialized deals with a strange drug smuggling gang, then the second episode was published as a supplement (this one) instead of being serialized on Shonen.
What is fascinating about it (besides the fact that being a supplement it has a great custom cover) is that it is a story that deals with the nostalgia for parents, which is a central element in Astro Boy as being a robot he did not have actual parents, besides Dr. Tenma. What is fascinating is that in this original version Dr. Tenma is featured, and plays a prominent part, but when Tezuka re-did the story for the 1960s and then 1970s reprints, he is completely omitted, and there is just Ochanomizu.
Also, there is a touching opening sequence where, right before Christmas, Astro gifts away his clothes, one by one, to poor and starving people, and as a last gesture, he gives away his synthetic skin to a mother with a small child trembling for the cold. This complex scene is somewhat simplified in the redone version, and he just gives people his clothes.