Mankind's Survival of the Fittest

Mankind's Survival of the Fittest is a series of 6 bonus episodes that were included with physical releases of Humanity Has Declined in Japan. Each episode is 2 minutes long and it chronicles an absurd side-story where The Mediator confiscates some fairy tools, including a strange spoon that seems to turn her thoughts into flour that can be used to bake sweets. After gathering a lot of flour, she wakes up the next day realizing she has been shrunk down to the size of a fairy.

After failing to enlist the help of her Grandpa, The Mediator leaves the house in search of the fairies who made the spoon. She encounters Yameta along the way and is chased into a pond by weasels, where she is then found by a number of fairies, who now resemble humans. The Mediator uses the spoon again to make more cookies, only to find herself shrinking further and becoming even dumber, now unable to remember who she is and what she was trying to achieve. The Fairies bring her to her own house, claiming the Goddess there can help with anything. They bake cookies with the flour left behind by The Mediator's first usage of the spoon, which helps her regain some level of critical thinking. The Mediator then convinces her fairy friends that the cookies are poisoned and eats them all herself, restoring most of the intelligence and height.