People on Earth celebrate 'Memory Day' to honor loved ones who live on other planets. The robots participate by agreeing to impersonate the absent family members for the day. Astro volunteers to pose as a little boy for his parents. Complications arise as Astro tries to mimic the son's nervous ticks and eat his favorite foods (in abundance!!!) Adding to the problems is the fact that the missing boy's older brother has gotten involved with a group of gangsters.
(special thanks go to Raquel in Alabama for helping to fill in details on this one, which I've only seen in its original Japanese version)